Camber Tires...

[MPREZIV]

http://www.autoweek.com/article/2010...NEWS/101009954

Discuss amongst yourselves.


And the link to the company's website.

http://www.cambertire.com/

[Dean]

I am confused. He says they have a larger diameter on the outside???

That would make them positive camber tires sort of.

I guess the theory is to negate the wear and overheating of the inside of the inside tire and preload the outer edge of the outer tire???

I think Hoosier did the opposite in the past with some of their designs.


Thinking about how tires wear in autocross and such, he may be on to something. A loaded outer tire is unlikely to be ably to actually lift the inner portion of the contact patch and the outer sidewall is already preloaded so grip is already present prior to tire angle change... I think this might greatly reduce the tendency for the tire to roll under which is what cause all the shoulder wear.

Hmmm.

[rory_a]

"Work on his next innovation, called Rockers, is also being done. They are molded shoulders on a tire's sidewall that only come in contact with the ground during cornering for improved performance and stability"

If I understand that right, his next big thing is a semblance of over-inflated tires?



The Camber Tire concept seems like it would work for cars with lots of negative camber - run lots of negative with a tire that has positive so that with body/tire roll in turn you get a net of larger contact patch. But, if the intention of additional negative camber for Subarus is to increase contact patch when loading up in a turn, wouldn't this be counterproductive? It's basically allowing you to run less camber considering the amount of camber built into the tire. But that means that when you optimize the camber curve of the suspension, your net between static suspension camber and static tire camber is well outside of the optimum for the car's characteristics, no?

So maybe this is a decent concept for the "HellaFlush" croud? Where's the GTI/18x10" Subaru guys for input?????


I can see this being of great benefit for a dumped swing-axle car with 4+* of negative rear camber - you end up with a decent contact patch when running the tires opposite of what they were intended (inside out). Then again, that would be limited to dumped pre-'67 Volkswagens, and I've yet to meet an owner of a dumped swing-axle Volkswagen that gave a sh*t about handling.

[rory_a]

A few years ago Lib Tech brought the concept of rocker/negative camber back to the snowboard industry - with their first snowboard shaped like a banana. The concept was initially met with great disbelief, until people actually toke on for a ride. Now about half the snowboards offered this year (industry wide) are negative camber.



Ironically, it's a direct opposite use of camber to these tires - REDUCING your static contact patch for greater speed, greater turn control, and greater "pop".


The rocker tires, in a similar way, might offer the exact same thing - reduced static contact patch in order to allow for greater contact patch when one or the other side is loaded up. Might be an interesting concept if they can pull it off.

[sperry]

Imagine tipping a cone over onto a table top. Now roll that cone. Now explain to me how a cone shaped tire can do anything but wear more quickly than a cylindrical tire.

Frankly, this "invention" reeks of a bandaid to poor suspension geometry. Also, it reeks of "prior art" since people have been shaving tires asymmetrically since the 60's in SCCA.

Somewhere there's a massive NASIOC thread about this from a month or so back.

[MPREZIV]

Originally Posted by sperry

Imagine tipping a cone over onto a table top. Now roll that cone. Now explain to me how a cone shaped tire can do anything but wear more quickly than a cylindrical tire...

This was the first thing out of my mouth as well... Just didn't make much sense how two cylindrical tires on the same axle can do anything but have a serious push in toward one another.

[cody]

The inventor, John Scott, seems to be getting pretty butt hurt if you read his latest response below the article.

[Dean]

When you tip(negative camber) and compress a cylindrical tire, what do you think happens? It acts like a cone. The outer edge has to move faster or inner edge slower and/or deflect and generate heat/wear.

It sounds like from the angles he is talking about, you are just changing from a -1 degree to a +1 degree cone. Wear should be similar in either case, you are just changing what is preloaded.


Tire dynamics are not well understood especially by me, but I can understand where moving the preload form the inner to outer edge might improve all sorts of things.

Suspension designers have been trying to maximize wear, performance, noise, etc with cylindrical tires forever with many trade offs.

Negative camber is supposed to lay the tire flatter under cornering load to increase contact area on the outer tire and minimize roll under of the sidewall. One of the problems with it as we have all experienced is if you change input to quickly, the tire can start to slip before the outer edge can grip since you only have the smaller inner contact patch. You also have the other negative of the inner tire's contact patch getting very small.

I am guessing is that by changing the geometry and characteristics of the outer sidewall itself to minimize roll under and have the most important outside edge preloaded that you might see substantial improvement in initial traction at turn in or in emergency maneuvers. You also would not loose contact patch on the inside.

In effect, you are increasing the spring rate of the outer edge of the tire which could be very helpful.

I am not saying this is the greatest thing since sliced bread, far from it. In a perfect world, we would get the suspension, wheel and the tire folks together and potentially build the perfect combination for a given set of circumstances. If you put the suspension back at zero camber, what tire design works best? Maybe we need wheels that are 1" larger on the outer edge than inner edge?

Just because tires have always been cylinders doesn't mean that is the best shape for them. Asymmetrical and directional tires are now very common, why not asymmetrical sidewalls? I applaud the guy for thinking outside the box and challenging conventional wisdom.

[sperry]

Originally Posted by cody

The inventor, John Scott, seems to be getting pretty butt hurt if you read his latest response below the article.

Geesh... that dude needs to shut up and let the tire do the talking. Getting e-butthurt online is not exactly the most professional way to sell your new product.

Here's the test I want to see: Start with an excellent handling car with ideal suspension geometry... say a Lotus Elise or something and put adjustable bits on it. Set up the car with normal tires, and allow the tester to make any suspension changes they'd like. Tune the suspension and get the max performance numbers.

Now, switch to the cambertire with an equivalent compound. Reset all the suspension settings and tune the suspension again. Get those max performance numbers.

Now run both setups for a long ass time and see how tire wear compares.

Compare the numbers, if the cambertire is significantly grippier and/or longer lasting, dude may be on to something. However, my guess is that tire just compensates for poor suspension setup on most cars, so it seems better without actually being better.

[sperry]

Originally Posted by Dean

I applaud the guy for thinking outside the box and challenging conventional wisdom.

That's the funniest part about this. People have been shaving tires asymmetrically for years to try to get better handling in SCCA stock classes where camber adjustments aren't allowed outside of factory specs. This is not a new idea... it's a 40+ year old idea to bandaid suspension geometry issues.

Call me skeptical. I just think that if this idea had real merit, the folks at Hoosier, Goodyear, Bridgestone and Michelin would have sorted this out decades ago when they were battling each other in F1. The reason they haven't bothered with this level of asymmetry is because suspension changes are more useful.

Now, maybe there's a market for these tires in that you can slap them on a car with no other changes and get better handling. But who knows how the auto manufacturers will take to that as far as warranty on stuff like wheel bearings goes. We may see warranty work start getting denied over non-standard sized tires.

And maybe this guy really is on to something, and we'll see a revolution in tire design come out of this. Though, I do get the feeling that this guy is going to have a patent war on his hands if that's the case... because this idea is not as new as it seems, unless he's also patented tire manufacturing methods or something for this cone-shaped tire.

Either way, I'm skeptical. I'm totally willing to be proven wrong, but that's what's going to have to happen for me to believe. I want to see an apples to apples comparison where of two cars optimized for their tires, the cambertire car is faster.

[Dean]

I agree Scott that the proof is in the science/testing. You might need even more adjustability though. Even the Elise makes assumptions about tire/wheel design.

In some respects, what he has done is widen the track of the car. You could do the same thing by using positive camber on normal tires, but they would roll under like a SOB.

What we need is a tire that is less compliant laterally and more compliant vertically.

To go even further than the camber tires, maybe the real issue is with tire/wheel attachment. You could make a tire much more resistant to lateral forces if you could angle the attachment at the rim. Maybe a 15-30 degree angle would be nice as long as it supported the lateral load component without debeading.

[Dean]

Originally Posted by sperry

That's the funniest part about this. People have been shaving tires asymmetrically for years to try to get better handling in SCCA stock classes where camber adjustments aren't allowed outside of factory specs. This is not a new idea... it's a 40+ year old idea to bandaid suspension geometry issues.

You are correct, but they were/are doing it for more negative camber, not positive which is what he is doing. Camber is really the wrong word here.

Racers have been shaving smaller outer, larger inner diameter, he is doing the opposite, larger outer, smaller inner.

He is challenging the basic concept of negative camber is good which is why everyone else has their panties in a bunch over this. He is tilting at windmills.

Again, not speaking for him, but I can see where having a traction at the outer edge of the tire from the get go when cornering might be a good thing as long as you can keep the tire from deflecting and eating the sidewall. And keeping the inside tire in contact can't be a bad thing either. NASCAR run the inners at positive camber after all for just that reason. If he can generate a net gain in overall traction while effectively increasing the track of the car, he might well be on to something.

[sperry]

Originally Posted by Dean

You are correct, but they were/are doing it for more negative camber, not positive which is what he is doing. Camber is really the wrong word here.

Racers have been shaving smaller outer, larger inner diameter, he is doing the opposite, larger outer, smaller inner.

How is that fundamentally different, from a patent/prior art perspective? Modifying the tire for asymmetric diameter, is modifying the tire for asymmetric diameter regardless of whether it's + or -.

[Dean]

Originally Posted by sperry

How is that fundamentally different, from a patent/prior art perspective? Modifying the tire for asymmetric diameter, is modifying the tire for asymmetric diameter regardless of whether it's + or -.

Changing sidewall height/angle and design/construction may be unique enough to be patentable. Just shaving the tire the other way would not be. heck, there are probably hundreds of patents on minor variations of the classic cylindrical tire.

But I am not really interested in that aspect. The physics is far more interesting to me.

I'd love to hear from Austin on the geometry aspects.

If at turn in, you effectively move whatever the outside point is called on the leg from the CG to the effective outside contact point of the tire, how that impacts things.

I talk about camber theory all the time in my classroom sessions, and I wonder if some of what I have been saying is wrong or at least not entirely correct if tires were different.

[knucklesplitter]

Originally Posted by Dean

Just because tires have always been cylinders doesn't mean that is the best shape for them. Asymmetrical and directional tires are now very common, why not asymmetrical sidewalls?

High Performance directional tires already have asymmetrical sidewalls, not necessarily the shape or diameter, but the components that go into the sidewalls on an uncured tire are different on the outside to inside.

[Dean]

Originally Posted by knucklesplitter

High Performance directional tires already have asymmetrical sidewalls, not necessarily the shape or diameter, but the components that go into the sidewalls on an uncured tire are different on the outside to inside.

I know.

[knucklesplitter]

Originally Posted by Dean

I know.

It's good to know that you know I know...