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Transportation Technology

Cambered Tires Can Improve Fuel Economy 317

Posted by timothy
from the my-heart-has-four-cambers dept.
thecarchik writes with an excerpt from Green Car Reports: "We already know that it's possible to curb your fuel consumption just by having your tires properly inflated, or better yet, installing a set of low rolling-resistance tires, however, soon there may be an additional avenue to look at when picking the most fuel efficient rubber for your ride. The answer is the camber of your tires, more specifically, the negative camber. This is when the tops of your car's tires are angled inwards towards the chassis. Of course, there are negative effects too — namely increased tire wear and impaired ride quality — which is why production cars almost always have zero camber." The linked article, as well as the New York Times article from which it draws, describe a new tire which is designed to minimize those negative effects.
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Cambered Tires Can Improve Fuel Economy

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  • "Negative Effects" (Score:3, Insightful)

    by JakiChan (141719) on Sunday August 15, 2010 @10:44PM (#33260354)

    If you ask me it IMPROVES ride quality. Some of us don't like driving a car that feels like an overstuffed sofa on wheels.

    • by JazzyJ (1995) on Sunday August 15, 2010 @10:50PM (#33260378) Homepage Journal

      Perhaps you should get your shocks replaced....

    • by aoteoroa (596031) on Sunday August 15, 2010 @11:40PM (#33260650)
      I wonder if the increased fuel efficiency is simply the result of creating a smaller contact patch for the tires and reducing the rolling resistance. Maybe the same result could be acheived by using skinnier tires...but they wouldn't look as cool.
      • by Lt.Hawkins (17467) on Monday August 16, 2010 @01:01AM (#33260988) Homepage

        if thats so... I don't want one (or four?). I want larger contact patches for better stopping. Screw 1 MPG, I don't want to hit that kid / dog / train that ran out in front of me.

        • Re: (Score:3, Funny)

          I'm just imagining a boy with a dog running out in front of you along the railroad tracks. Or even more absurd, a train flying out in front of you in the middle of the suburbs with no tracks in sight.

          Why do I suddenly feel like watching back to the future?...
        • Re: (Score:3, Interesting)

          by CheshireCatCO (185193)

          I agree. I had higher-pressure tires that came with my Civic Hybrid. This past year, they finally were to the point of needing replacement. Having moved to Minnesota (from Colorado) in the meantime, I went with regular tires for the somewhat better traction. My mileage has dropped maybe 1 MPG as a result and traction seems noticeably better in rough weather. (It's a bit of apples and oranges to compare, of course.)

          On the other hand, in Colorado I seldom had any traction problems with the high-pressure

          • Re: (Score:3, Insightful)

            by Lumpy (12016)

            That's why most people that are smart in those states have 2 sets of tires.

            1 summer set.
            1 winter set.

            I like the high pressure low rolling resistance for summer. I have real winter tires for the winter.

            Result? My honda civic has an easier time in snow than any 4WD SUV and their "all season" junk tires. (Yes, your $500.00 each boutique all season tires are JUNK!) I can go up icy hills that have an escalade owner crying over. I have regularly went through 2 foot of snowfall on the road without problem.

            Snow

      • Does narrower = less rolling resistance? Wikipedia seems to suggest otherwise [wikipedia.org], but to be honest I don't really understand what it's saying. Can anyone clarify?

      • Re: (Score:3, Insightful)

        by mwvdlee (775178)

        Think of all the fuel required for cremating the dead body of traffic victims caused by those tires.

      • by Gordonjcp (186804) on Monday August 16, 2010 @02:45AM (#33261310) Homepage

        That's exactly what it is - the outer edge of the tyre has a lot less loading than the inner edge. Not only does this make the ride unpleasant but it drastically reduces grip and makes the car handle like a greasy weasel. If you want to know how to get the best out of your suspension, look at how tarmac rally cars are set up. That's going to be about the closest in "performance" suspension to what will be suitable for a daily driver. You'll find it has little camber, very soft springs with a lot of travel, and very stiff damping. On the road, this would give you a soft, comfortable ride with excellent grip on uneven road surfaces. Having really hard suspension means you have no grip at all, on anything but a perfectly glass-smooth racing track.

    • by no-body (127863)

      Yeah, like this: http://www.greencarreports.com/image/100174380_erwin-wurm039s-fat-car/ [greencarreports.com]

      Throwing out your existing tires for fuel economy? How much oil is in those tires anyway?

      Add 2 PSI to regular tire pressure and your roll resistance goes down. Another great factor is driving style and type of car.

      Bigger topic..

    • Re: (Score:3, Informative)

      by Lumpy (12016)

      Have you ever driven a zero camber set car? They are twitchy as hell. even slight negative camber is still a challenge to drive. Considering what I observer daily in the lack of skill in driving that most of the population has, I really don't want to encourage making the job harder.

      Yes Zero or slightly negative camber increases gas mileage and it has been done for decades for mileage challenges, and is certainly not new. Having driven a car that had zero camber setup for max fuel economy and running on

      • Re: (Score:3, Informative)

        by Anonymous Coward

        I think you may mean Toe? Most cars have zero camber, or very close to it. Toe at zero or toe out is what causes a very twitchy car.

  • How? (Score:5, Insightful)

    by Sarten-X (1102295) on Sunday August 15, 2010 @10:44PM (#33260360) Homepage
    How does this help fuel economy? More to the point, how is this story anything but an advertisement for some guy's new tire?
    • Re:How? (Score:5, Informative)

      by DevConcepts (1194347) on Sunday August 15, 2010 @10:52PM (#33260390)

      In a pure theory aspect, less tire on the road, less rolling resistance.

      • Re:How? (Score:5, Insightful)

        by Lotana (842533) on Monday August 16, 2010 @01:33AM (#33261084)

        In a pure theory aspect, less tire on the road, less rolling resistance.

        Now I am completely new to this whole area, so please don't flame me too hard if what I ask is something stupid and obvious.

        It is logical that less friction, less power is needed to keep the wheel spinning. But in poor, wet or icy conditions I need every unit of friction possible for safety (Aside: What is the unit of measure for friction?). Therefore, isn't this new tire design makes it more difficult for me to brake and thus more hazardous?

        Saving me money in fuel is good, but if some child runs out in front of my car on local road and I can't stop in time with these tires...

        • by initialE (758110)

          Wonder if it is possible to design a tire that changes its rolling resistance according to the speed with which it is rotating.

          • Re:How? (Score:4, Insightful)

            by tknd (979052) on Monday August 16, 2010 @03:39AM (#33261502)

            That wouldn't solve anything. You'd want to change the properties depending on if the driver is trying to stop or not. Such a tire you're suggesting wouldn't do anything for me if I'm trying to stop at 70mph.

            The best I can imagine is a self-inflating/deflating tire. If the driver presses the brakes and the tire starts to lose grip, the tire would deflate some to increase contact with the road. Similarly, when the tire is not in any pressure to stop/accelerate or turn, the tire would over inflate to reduce resistance.

            Such a device might be feasible. It would require a wirelessly controlled pump attached to the tire and it would probably be integrated with the TPMS system (which is already wireless). But the pump would need to be powered somehow. Seems a bit complicated and expensive to design and another point of failure. Who knows, maybe we'll hit a point where fuel/energy is that much more expensive so implementing a device is worth it.

            We could also simplify the problem and just over inflate in optimal conditions and have a special valve that resets tire pressure to normal when bad conditions are detected. A pump would still be necessary, it just wouldn't have to be as demanding since the under-inflated case is out of the equation.

            But for some people this system could be a net loss. Some drivers jam the hell out of their brakes that their brake pads go like nothing. I knew a friend's dad that burned through new brake pads in just a few months. The system would probably spend more energy adjusting tire pressure because it could never tell when the driver really needed to stop.

          • Re: (Score:3, Funny)

            by xelah (176252)
            Or have an extra set of wheels that drop down when necessary. Or go all the way and fit rockets (plus some on the sides for cornering). What could possibly go wrong?
        • Re:How? (Score:5, Informative)

          by chrylis (262281) on Monday August 16, 2010 @02:59AM (#33261366)

          The coefficient of friction is dimensionless; it's the ratio of the maximum frictional force (opposing motion) to the force pressing the two objects together (such as the upper object's weight).

        • Re:How? (Score:4, Informative)

          by R.Mo_Robert (737913) on Monday August 16, 2010 @03:10AM (#33261396)

          Aside: What is the unit of measure for friction?

          Friction itself a force; therefore, you can measure it in Newtons (or poundals or your unit of choice). However, most non-physicists (that's me! ...so correct me if I'm wrong, by the way) run into the coefficient of friction far more frequently. This number (usually represented by the Greek letter mu) is just a ratio, so there are no units. (This probably explains the confusion in the first place.)

        • by beelsebob (529313)

          Dead right, these will indeed reduce friction with the road and become dangerous in the winter, or even when trying to do an emergency stop. The unit of friction, it being a force, is Newtons by the way.

      • Yes, and less rolling resistance means longer stopping distances.
    • Re: (Score:2, Interesting)

      by thesupraman (179040)

      I suspect this is pure stupidity along the lines of the contact area, hence friction would be lower.

      Of course just using a narrower tire does the same thing, but since everyone wants to see
      nice wide tires under their cars....

      On a poorly designed suspension setup you could get more grip in corners thana narrower tire
      like this, but that is in effect a design fault.

      And ihave a strong doubt there is anything they can do to mitigate the wear problems except
      make tires with thicker tread on one side, which is doub

      • Re: (Score:3, Insightful)

        by LurkerXXX (667952)

        On a poorly designed suspension setup you could get more grip in corners thana narrower tire
        like this, but that is in effect a design fault.

        Just about every sports or race cars out there ( including Formula 1) have negative camber. You are saying that is a design default? Righhhhhht.

        • by sheddd (592499)

          If I may be so bold as to guess what the grandparent meant:

          "If the car doesn't have a touch of camber in turns (whether thru camber, caster or other adjustment) then it's got a shittily designed or tuned suspension and this stupid tire might make it work better."

        • Re:How? (Score:5, Informative)

          by thesupraman (179040) on Sunday August 15, 2010 @11:14PM (#33260506)

          Sigh, go and learn something you retard.

          They dont, any competent and not class limited suspension design dynamically adjusts camers in corners to develop the desired cornering camber, while not causing issues in strange line.

          A lot of moronic 'boy racers' like to think a ton of negative camber is the sign of a race car, mainly because some suspensions designs develop a lot of un-adjustable negative camber when cars are over-lowerd.. This of course is terrible for handling (but they like to think it is not.) but since those cars cannot have it adjusted out with spending real money....

          And F1 most certainly does NOT run static negative camber, it would be a disaster for straight-line handling. They run DYANMIC camber in corners due to the uneven A arm suspension geometries.

          I suggest you start here.

          http://www.amazon.com/Competition-Car-Suspension-Construction-Motoring/dp/085429645X
          http://books.sae.org/book-pt-90

          • Re: (Score:2, Troll)

            Wow, a few seconds on google and I found something that contradicts your statement about camber.

            The amounts of camber gain varies from car to car, team to team and even by the engineer’s philosophy on suspension set-up.

            and

            Pushing the bodywork down (such as when the wings develop down-force) compresses the suspension, and if the car has a camber gain curve, the camber angle will increase. This change in camber may be desirable during high speed cornering

            Found this here [suite101.com].

            Since your such the expe
          • Sorry, I missed the part in your posting about "static" camber, something the OP never mentioned. In that regard you are correct. Perhaps next time you should try taking a less aggressive tone and more people will understand what your saying rather than being distracted by thoughts of you being various parts of a horse.
          • "Boy racer"-isms coming from "thesupraman". Awesome.

            Hard to bash Supra's with stuff like this, though:
            The Texas Mile [viperalley.com].

          • Re:How? (Score:5, Insightful)

            by Sycraft-fu (314770) on Monday August 16, 2010 @12:19AM (#33260828)

            Also I wish that people would stop looking at how race cars do things and assume that it is good. Race cars are specialized machines designed for a specific purpose. They are good at what they do, but that doesn't mean they are good at everything.

            For example you would find that many kinds of race cars would have real trouble handling on normal roads. They rely on the downforce generated by their high speeds and the heat changing the properties of their tires. On regular surface streets and speeds, they don't perform so well.

            Likewise you wouldn't want a racing engine. Not only could you not use it but those things aren't built for longevity. The cars badly tear themselves up over the course of a race. The engines are pushed to extremes. However they needn't survive for more than a single race, another one can be had next time around. Wouldn't be so nice on a regular car though (even though it would last longer due to being used less intensely).

            If you want to drive a car on the street then, well, you want a street car. It turns out the engineers behind them are usually fairly savvy and the design decisions are made for a reason. This includes things like the camber of the wheels.

            If you are going to race a car, great, then you probably do want to modify it and there are some cool classes of racing purely on modified street cars. However realize that it is expensive, and generally you have to do a good deal of mods for it to be worthwhile. Don't just lower your car and think that matters to any real degree. While lowering the suspension is likely to be something done in converting a car for racing, that doesn't mean that lowering it alone is going to get you anything driving around town, other than some scrapes from speed bumps.

            And really, if what you want is more performance in a street car, you just need to spend more and buy a more performance street car. Go get an Audi S4 or something. It'll have more power and speed than you can use on any street outside of the autobahn.

            • Re:How? (Score:5, Informative)

              by LurkerXXX (667952) on Monday August 16, 2010 @12:46AM (#33260930)

              Also I wish that people would stop looking at how race cars do things and assume that it is good.

              No one said a negative camber is good in all circumstances just because most sports cars use it. Heck, on Indy cars, they often have positive camber on one side of the car because they always turn one direction. Even among racers, they adjust the amount of camber by what type of course they are going to be racing on. In many cases for every day personal cars, 0 or close to 0 camber is the best setting, for others a slight negative camber is going to work best. The point was not that every car should use negative camber. It's that saying "negative camber is a a design defect" is moronic.

            • by poptones (653660) on Monday August 16, 2010 @04:06AM (#33261566) Journal

              I was a mech for many years and grew up in Detroit. Just about ewveryone I knew worked in the auto industry, and I myself worked in the auto industry as an engineer.

              And just about every car I have ever worked on or known about specifies some amount of negative camber right from the factory. You can call this anedote if you like, but the fact is I've worked on LOTS of cars and seen a LOT of specs and have seen zero or positive camber specified on a car so few times I could probably count them all on one hand.

                Because it's NOT just about how the car grips in the corners, but how it handles in a straight line; Too much negative camber will make the car twitchy as it bump steers over every wave or truck rut, but NO negative camber also makes the steering feel lighter, which is also not a good thing when it means the car has absolutely no "return to center" correction. Any rear wheel drive car will try (to some degree) to straighten itself out, but half a degree to two degrees (depends on car) negative camber is pretty much standard. Part of this is also because cars tend to get knocked out of alignment because of neglect, and POSITIVE camber is really no fun - it tends to make the car even more vague in steering. So a little negative camber is built in just to help make certain things don't go positive.Of course too much is also no fun, since it will make the car try to steer away from the crown in the road and heavily crowned roads will make you feel like the front end is badly out of alignment (because it is).

              The same holds true for caster: toe the front wheels out a bit and the thing will wander all over the place; toe them in and the car will tend to center itself. Both of these also will tend to increase friction as well, which also it seems would negatively affect mileage. Given many cars nowdays run on low profile tires inflated to 40psi or more I have a hard time believing it's going to make much difference on a properly tuned and aligned vehicle, however.

              • by mungtor (306258) on Monday August 16, 2010 @07:32AM (#33262160)

                The same holds true for caster: toe the front wheels out a bit and the thing will wander all over the place; toe them in and the car will tend to center itself. Both of these also will tend to increase friction as well, which also it seems would negatively affect mileage. Given many cars nowdays run on low profile tires inflated to 40psi or more I have a hard time believing it's going to make much difference on a properly tuned and aligned vehicle, however.

                I'm hoping you just mis-spoke here, or that you're not a suspension engineer. Caster and toe are completely different entities. Toe is whether your tires are pointed inward (toe-in) or outward (toe-out) when viewed from the top. Caster is a measurement of how far the center of the contact patch is behind the steering axis. Caster is what makes the wheel want to straighten out. Both toe and caster are much more important for straight line stability than camber is.

        • Re:How? (Score:5, Insightful)

          by JWSmythe (446288) <jwsmythe@jwsm[ ]e.com ['yth' in gap]> on Monday August 16, 2010 @12:18AM (#33260824) Homepage Journal

              Race cars are made to turn quickly. Street cars are made to drive on relatively straight roads. There's a huge difference in the setup of the vehicle.

              Oval track cars give negative camber to the right side, and 0 camber on the left. That's because they always turn left. They even adjust their brake systems to assist in this (more braking power on the left side). As the car turns left, the body rolls to the right, shifting the weight to the right, and increasing the surface area on the right contacting the track.

              Street track cars (like Formula 1) expect to turn both left and right, so they get negative camber on both sides. Regardless of the direction they turn, the body rolls (much less, but it still does), and the weight is transferred to the outside of the turn. As that happens, the negative camber comes closer to 0. At a stop, sure it looks odd. In practice, it's what keeps them on the track.

              If you set up a race car like a street car (0 camber), you would see a race car that fails to perform as well as its peers.

              If you set up a street car like a race car, you'll be able to corner a lot better, but you'll reduce your braking ability in straight line stops, and your tires will wear significantly faster.

              With the negative camber tires, as the body rolls, they'll suffer the same fate. Instead of riding on the largest part of the tire (the tread), they'll roll up onto the outer edge.

              We won't see these tires showing up on production cars any time soon. If they are even produced, they'll be a sad fad like the Aquatred tires. The original version (circa 1991) They increased resistance to hydroplaning, but reduced overall traction due to less surface area contacting the road. The better innovation was improved groove patterns to reduce hydroplaning while still maintaining a large contact area. The Aquatred II and Aquatred III kept the brand name (and hype), but operate like a normal tire with good tread patterns.

              If this does make it to market, I'd shelve it right along with the fuel line magnets that align the atoms of the gasoline (or whatever); the electric supercharger that is only a marine bilge fan; and my all time favorite the battery cover insert for your cell phone that will increase your signal by 1000%.

              I'd never compare it to a tinfoil hat though, those really work. Aliens, nor the government, have ever read my thoughts from space. :)

          • by AK Marc (707885)
            As the car turns left, the body rolls to the right, shifting the weight to the right, and increasing the surface area on the right contacting the track.

            Weight shift is a result of the turn, not the body roll. A car with no body roll would still have weight shift in a corner.
        • by PsychicX (866028)
          Many "normal" cars that are meant to be even vaguely sporty or fun to drive run a degree or two of negative camber as well. It's pretty much vital for reasonable cornering.
        • by beelsebob (529313)

          Just about every sports or race cars out there ( including Formula 1) have negative camber. You are saying that is a design default? Righhhhhht.

          Formula one cars also use tires with no tread, and about a foot wide. These too would be a design flaw on road cars.

      • Re: (Score:3, Funny)

        by Ihmhi (1206036)

        The fact is, if you care, just run narrower and harder tires.. Thus giving lower friction and
        more economy, duh!

        Ah, so that's why my mountain bike uses so little gas. Makes sense!

      • I think maybe you misunderstand the fundamentals of automobile suspension. On the one hand, you are correct in that narrow tires provide better economy. At the expense of grip. On the other hand, you seem to think that tire camber doesn't change during corning, which is flat wrong, and defys physics.

        For road cars, which do not need or usually want to corner at very high velocities, the suspension is designed to keep as close to zero camber as possible. This provides the best ride, while still allowin
  • BMWs, Minis (Score:3, Interesting)

    by Raleel (30913) on Sunday August 15, 2010 @10:48PM (#33260372)

    Apparently, BMWs and Minis (and probably other sport-ish cars) are negative cambered because it helps with handling. I found this out replacing the tires on my mini... the ones that I burned through in 1.5 years because I drive it like a sport-ish car ;)

    • I don't know anything about minis in particular, so maybe this question is stupid/redundant, but why didn't you rotate your tires to even the wear out?
      • Re:BMWs, Minis (Score:4, Informative)

        by SydShamino (547793) on Sunday August 15, 2010 @11:34PM (#33260622)

        I have a BMW, not a mini, but my car's tires (645ci) are completely different front-to-back, plus the tires are designed for single-direction turning only (i.e. grip works one way, not the other). Put those together and my car's tires can't rotate. They stay where installed until they wear out, which the rear tires already have done once in less than a year.

        Then again, there's these really nice, sharp corners on the freeway that I can take at posted speed (though never higher, of course) when most people slow down to 45... $350 tires (each) is part of what I bought when I picked the car.

        My rear tires have a static negative camber. I have no idea if it helps the abysmal fuel economy or not, nor does it really matter. I offset the carbon in other ways and I don't care about the cost.

        • The tire grip also differs from inside to out to handle corners, so I can't rotate the tires side-to-side by putting the inner surfaces out, either.

          1. No rotate front to back.
          2. No rotate side to side by flipping the direction the tires turn.
          3. No rotate side to side by setting the tires inside-out.

        • by aXis100 (690904) on Monday August 16, 2010 @02:29AM (#33261262)

          The salesman must have loved you. Would you like some special monster cable for your headlights too?

          I can do posted speeds on my $110 tyres, pretty sure it's not that lofty a goal.

          • Re:BMWs, Minis (Score:5, Informative)

            by Anonymous Coward on Monday August 16, 2010 @03:29AM (#33261470)

            Whether he needed it or not is debatable, but the points about different front/back tires and unidirectional tread are not snake oil.

            Particularly in rear-wheel drive cars, it is not uncommon for the drive wheels (which need to apply torque) to be wider, while the steering wheels (which may need to cut through water/snow) are narrower.

            Unidirectional tread is less common, but it does help reduce hydroplaning.

            If you have just one of these, you can still move your tires in one direction (not full rotation, but front/back or side/side). If you have both, you have to keep your tires in the same location.

          • Re: (Score:3, Interesting)

            by Lumpy (12016)

            Agreed, I have $110.00 Eagle GT II's on my pontiac fiero and I am certain I can eat his big heavy saloon BMW hard in the corners (and the straights with it's 528hp V8 I swapped in and added a turbo to bring me to 5lbs per HP makes it nearly twice as fast than his 9lbs per HP..) When I do track days I will swap to MT's simply for the grip, but they have a problem that 90% of drivers never understand. they grip hard until they cant anymore, then they let go completely. It's like you fell off a cliff. G

      • by Aranykai (1053846)

        It wouldn't address camber wear because the inside of the tire is still the inside. Unless you remount them on the wheel, the same part of the tire is in contact with the road.

    • Re: (Score:2, Informative)

      by Anonymous Coward

      Not uncommon. I have an older volvo wagon (245) Many owners have modified the stock arrangement to allow for a small increase in negative camber. Most people end up with -.5 to -1.5 degrees after some grinding and or drilling (nothing drastic). Upshot? A pretty much universal agreement that it improves cornering DRASTICALLY, and improves tire wear also. That's right most people report a noticble *improvement* in tire wear. (my car is stock and wears the tires unevenly FWIW) There are alot of variables

    • Minis and sport-ish in the same sentence? Someone watched a specific Hollywood movie (The Italian Job) a bit too much.

      They have a big cool-factor in the mind of most people (especially chicks), but for having owned a 1.6 turbocharged version, they remain quite slow, compared to other cars in the same price range. 9 seconds for a 0-60 is less than stellar, but then again, it's the same engine as what you get on a Peugeot 207 GT (or whatever they're called).

  • Exaggerated? (Score:5, Insightful)

    by grantek (979387) on Sunday August 15, 2010 @10:51PM (#33260386)

    TFA is light on details, and I fail to see how anything other than zero camber can be optimal for straight-line travel. I can see how it could reduce rolling resistance during cornering (in the same way it improves grip), but if you're looking to improve braking as the article claims, I'd be looking at caster (angling the wheel forward like the front wheel of a "chopped" motorbike) before camber.

    • I'm not seeing how this improves fuel efficiency unless you're always turning. Unless you live on a winding road, it's hard to see how someone is on a tight enough curve for this to change efficiency on typical roads.

      A lot of cars seem to have enough caster built into their suspensions, I don't know how increasing that will change efficiency. Another thing to consider is that changing caster probably won't require special tires, and this guy is out to sell special tires. I would guess that it's more an a

      • Re: (Score:2, Flamebait)

        by Joce640k (829181)

        SImple: Less tire area in contact with the road = less friction. Adding camber reduces that contact area.

        The guy in the article claims to have invented a tire which doesn't wear out so fast when you put camber in your suspension. That's what this is all about (reading comprehension!)

  • Well DUH! (Score:4, Insightful)

    by BLKMGK (34057) <morejunk4me&hotmail,com> on Sunday August 15, 2010 @10:53PM (#33260400) Homepage Journal

    Gee, less contact patch equals less friction and rolling resistance - and less traction with more treadwear on a narrower part of the tire if you get stupid about it. The car may also feel darty in a straight line but caster can also cause this. Auto manufacturers set alignments for more than just ride comfort and I'm pretty sure zero is NOT how many are set. Sheesh!

    I know, lets put bicycle tires on cars and bump pressure to 120PSI. Bet it will get great MPG! Never mind the side effects...

    • by BLKMGK (34057)

      That said - a cambered tires sounds interesting. Just not sure how having a cambered tire compensated for by an adjustment in camber on the suspension is going to do anything a properly adjusted suspension couldn't already do. WTF?

    • by Mashiki (184564)

      Funny story. I was doing my apprentice ship for a mechanic split between two shops, one day a guy rolls in with a spare and a fully blown out tire. I mean so blown out that various parts of the sidewall were missing, and the tread section was partially torn from the tire.

      Well that was fine, we sometimes see catastrophic failures of tires due to mechanical defects which is what this looked like. But in this case no. Checking the other 3 tires on the car, they'd been inflated to 110psi. Fun stuff, I'm sur

    • by drsquare (530038)

      Since when does lower contact area with the same weight mean less friction? That wasn't what I learnt at school.

      • Depending on the materials used, you could have the same net amount of friction. Generally through, at the cost of tire longevity. The "stickier" at tire is, the shorter its life will be. How often do you want to change them out?

  • by gmhowell (26755) <gmhowell@gmail.com> on Sunday August 15, 2010 @10:53PM (#33260404) Homepage Journal

    I don't really understand TFA. Could someone post a car analogy for me?

    • by Junta (36770) on Sunday August 15, 2010 @11:08PM (#33260474)

      It has to be a computer analogy. This is kinda like when you are uploading files, but need them to go faster. You do that by leaning the computer back so the bits flow out of the back of it faster. Same deal here.

      • by bobdotorg (598873)

        Whoa - hold on there cowboy. That's only if you're uploading heavy bits.

        • That's only if you're uploading heavy bits.

          No heavy bits. (unless you like that sort of thing.)

          What most slashdotters really want to know is how to optimize the motion of the naughty bits.
      • by Tokerat (150341)

        It's more like putting all the swap space on the outer disc tracks and installing the drive vertically so the arm moves in a downward motion when seeking towards swap - it makes paging in/out just a wee bit faster in situations because the drive arm gets there faster due to gravity assist.

        ...which is likely complete bullshit, but so are most of the car analogies I've read :-)

  • Why do you people keep pushing one that requires registration?? Here, Watch some Leno [autoblog.com]

  • This stuff has been messed with before, and we've stayed where we are for several reasons...

    ...also, the lower your rolling resistance, -it used to be- the lower your traction was--although supposedly they've fixed that some too.

    Also, has anyone considered how spookily this will change steering response?

    (I wonder why it seems like we're willing to exchange fuel economy for safety and aesthetics lately to such a degree. Huh.)
  • by Sierran (155611) on Sunday August 15, 2010 @11:03PM (#33260440)

    The summary and the article it was taken from are misleading and poorly written. They only use the term 'fuel efficiency' to describe one possible effect of mucking around with your tires in general, probably by increasing their pressure or using harder tires. However, the CamberTire appears to have nothing to do with tire rigidity - and hence fuel economy - whatsoever. What the article appears to describe is a tire which is optimized by shape for negative camber, in order to improve handling of the vehicle, without the faster tire wear that putting negative camber on regular symmetrical tires produces.

    WIth negative camber, the tire will be able to withstand more lateral force since it is angled out at the bottom, 'into' the turns. Thus it will be able to corner harder without losing grip.

    • by sheddd (592499)
      The only reason I see that this tire could theoretically grip more than a conventional tire is that for a given width of tire the contact patch will be larger on an asymmetrical tire. Just get wider rims/tires if you need more grip, narrower if you want more economy.
    • by adolf (21054)

      Lots of cars have negative camber.

      My old E36 BMW 325i, for instance, has a fair bit of negative camber specified for the front and the back.

      Having driven the car for six years, I feel qualified to state that the tires seem to wear very evenly, even when using the non-directional, mount-any-way-you-like, so-soft-it's-almost-funny Blizzaks that I use in the winter.

      They seem to last a good long time, too, compared to other cars that I've driven that have zero camber.

      YMMV.

    • by jrumney (197329)
      Normally negative tire camber would increase the fuel efficiency for the same reason it increases tire wear - reduced contact area with the road in a straight line in order to have maximum contact area when cornering. However, this setup changes the shape of the tire in a way that will negate both the fuel efficiency and the increased grip when cornering (as the cornering forces will push the tire up onto its side, the same as if you were running normal tires with neutral camber).
    • by TomXP411 (860000)

      The core problem with this idea is that the tire is essentially a cone. So when the tire is rolling in a straight line, the outside edge will be turning faster than the inside edge. This will produce more tire wear and more rolling resistance than a cylindrical tire, sort of defeating the purpose.

      The best way to improve handling would be to design a suspension system that introduces camber when the vehicle rolls into a turn, but does not introduce extra camber when the vehicle is carrying additional weight.

  • ...when inflated with nitrogen.

    • Re: (Score:2, Funny)

      by ushere (1015833)

      better yet, helium....

    • by zippthorne (748122) on Monday August 16, 2010 @07:23AM (#33262146) Journal

      True that. I fill all my tires with a low-grade nitrogen mix (only about 20% impurities.)

    • Re: (Score:3, Informative)

      by s122604 (1018036)
      There's nothing wrong with filling a tire with pure nitrogen.
      It will help, marginally, in corrosion resistance and pressure maintenance. Not enough to matter for most folks, but it's not snake oil...

      My local oil change price does it for free, so I get it. I wouldn't pay extra for it, but given the choice N2 versus air, I'll take the N2..
  • Wouldn't they do the same thing. Decrease friction = better gas mileage?

    But who cares I love my unpractical 35" Pro Comp Xtremes and my 16 mpg truck which I drive 100km to and from work 6 days per week.

  • Just what I need; tires that wear quicker. I couldn't give two shits about my mileage. Where are the inexpensive tires that don't deflate? Isn't there a honey-combed tire that I can afford, or will it put firestone-death-wheels out of business? Yeah, yeah, I know. They changed their name to bridgstone because they've had so many recalls over the past 80 years that people started getting a clue. I'd invent the wheels myself but I know I'd probably get hit with a piano on the way to the patent office. I
  • hmmm (Score:3, Insightful)

    by thatskinnyguy (1129515) on Sunday August 15, 2010 @11:56PM (#33260736)
    It's like dragging a car sideways to the tires for many miles. In what universe does this make sense?
    • Re: (Score:3, Informative)

      by iksbob (947407)

      I agree. We're talking about tires shaped like a slice of a cone. Anyone that has played with a cone shape as a child may recall that when laid on its side and rolled, a cone will pivot around its apex. So, these cone-segment tires would try to do the same thing. Even without the cone analogy, it should be apparent that the smaller inner-edge diameter will try to travel a shorter distance with each rotation than the outer-edge diameter. That difference will make the tire roll on a circular path if left to i

  • by wickerprints (1094741) on Monday August 16, 2010 @01:26AM (#33261066)

    have to take it to the logical extreme:

    http://www.youtube.com/watch?v=_r6ltUgtFWI [youtube.com]

    Pretty soon, all stock Toyotas and Hondas will look like this! XD

  • Everyone should camber their tires. I did this myself on my subaru rally car. It is very easy, just a couple of button presses on the old PS2 remote, and you have cambered tires. And your car looks way cooler.

    But I think you need to buy the racing body first.

  • This seems to be yet another one of those "look at my new patent (on an old idea)!" type of PRs.

    BFG race tires featured asymmetric sidewall construction in the 90's specifically to increase effective negative camber in situations where it was limited by race rules and the chassis.

    Mechanics of the Aysmmetric Construction [porschenet.com]

  • WAIT hold on guys, I just took a land vehicle dynamics class last semester and if I find my notes.....

    Oh here they are one sec let me find the section on Camber caster, and kingpin inclination angles

    alright first off rolling resistances

    influenced by:
    applied load
    inflation pressure
    tread design
    compound

    The primary cause of rolling resistance is hysteresis (or internal friction) of the tire material, which occurs as the tire flexes

    it increases with
    higher load
    higher tread design agressiveness (net to gross footpr

  • In fact, one of the main problems is friction. Perhaps the most economic solution would be Teflon Tyres; this would also increase road safety over time, as it will tend to remove the more aggressive drivers from traffic.

  • Nobody's thought of this, yet? My google-fu might be weak but in three pages of searching I didn't find anything quite what i had in mind.

  • is to get American car companies to produce more fuel-efficient cars, either with diesels or a petrol. Whatever works, otherwise, it's all gimmicks.

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