Cambered Tires Can Improve Fuel Economy

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.

Comments

How?

[Sarten-X]

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?

[DevConcepts]

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

Re:How?

[thesupraman]

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:How?

[JWSmythe]

    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. :)

Re:How?

[Lotana]

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...

Re:"Negative Effects"

[JazzyJ]

Perhaps you should get your shocks replaced....

Exaggerated?

[grantek]

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.

A little help

[gmhowell]

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

When it is a car thing..

[Junta]

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.

Re:BMWs, Minis

[Anonymous Coward]

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:Except it's not just racers

[mungtor]

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.