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

"Negative Effects"

[JakiChan]

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.

Re:"Negative Effects"

[aoteoroa]

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.

Re:"Negative Effects"

[Lt.Hawkins]

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:"Negative Effects"

[mwvdlee]

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

Re:"Negative Effects"

[Lumpy]

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 traction is 80% tires, 20% driver skill, get some snow tires and own the road in the winter.

Re:"Negative Effects"

[oldspewey]

There are things you don't see because they are not happening, and then there are things you don't see because they take place out of sight.

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?

[LurkerXXX]

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.

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?

[Sycraft-fu]

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?

[Anonymous Coward]

The real question is, "Is the money saved on fuel more than the amount you will increase spending on tires?" Don't cambered tires wear faster? ...not to mention a higher chance of punctures being irreparable, and thus necessitating early tire replacement?

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:How?

[tknd]

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:How?

[tehcyder]

Saving me money in fuel is good

Every fucking time on slashdot there's an article about saving fuel, all people can go on about is how much money it's saving. That's not the point, it's about overall reducing the amount of oil needed to stop it running out as quickly.

Re:How?

[Anonymous Coward]

No, it's about saving money. People don't give half a shit about reducing the oil consumption.

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.

Well DUH!

[BLKMGK]

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...

Camber changes as the suspension compresses.

[Anonymous Coward]

It's called dynamic camber. A car with 0 static camber at rest will gain some camber as it's suspension compresses because it pivots more or less around an axis. Those of us that do competitive driving will generally dial in static negative camber so that in a hard turn, the tire doing the work is near zero camber, and therefore has it's largest possible contact patch. Of course we drive around skating on the edge of our tires in a straight line, but that's OK, it just wears out the tires. Under acceleration weight shifts to the back of the car, compressing the rear, and getting you to zero while you need it (Assuming that you have a rear drive vehicle). Similarly, when you brake, weight shifts to the front of the car, bringing the camber on the front tires, and setting them us to work best when they are stopping the car. The fronts always do the majority of braking because of weight transfer.

So anyway, this guy as come up with a way to get a tire that is skinning when you need it (straight line friction reduction), and wide when you need it for cornering, acceleration and braking. It's conical rather than cylindrical. It's hard to say if the tire actually holds together for long straight trips, but I think the idea is sound and rather clever. I'm interested to see how the car would feel in transition. Grip would always start rather light and build as weight transfer brought more of the tire to bear.

More expensive tires that need replacing often

[networkzombie]

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'd call them Lux-O-Glides or maybe X-Flats-O-Matix.

hmmm

[thatskinnyguy]

It's like dragging a car sideways to the tires for many miles. In what universe does this make sense?

Ummm, sometimes the answer is in a book

[Sycraft-fu]

Sorry if that goes against the short attention span mentality we generally have these days, but that's life. Sometimes there isn't a good or reliable reference for something online, you have to go get a book.

"either way I win"

No not really. You may "win" in your own mind but that is meaningless. If you mean "win" as in convince others you are right, you have failed. Sorry.