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Cambered tires...increased skidpad holding, decreased braking distance

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Old 05-03-10 | 09:02 AM
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Default Cambered tires...increased skidpad holding, decreased braking distance



full story here --->http://www.automobilemag.com/feature...res/index.html

first part of the article....

In 1839, Charles Goodyear accidentally discovered how rubber could be 'vulcanized.' Since then, the most notable tire advancements can be counted on one hand. Scot Robert Thompson invented the pneumatic tire in 1846. (Forty-two years later, Dr. John Dunlop had to reinvent Thompson's discarded idea.) Michelin patented the steel-belted radial in 1946. Tubeless tires arrived in 1954 followed by the first run-flat designs in 1958 and low-profile sidewalls in 1968.

Add to this list of fearless pioneers John Scott who recently offered us what he calls a Camber Tire for testing and evaluation. In our June 2010 issue, Automobile Magazine selected this as one of the ten most significant emerging technologies. Now that we've enjoyed a few miles over the road on these tires and had the chance to conduct two preliminary performance tests, we're more convinced that the Camber Tire concept is worthy of our acclaim.

Twelve years ago, Scott -- a successful Wisconsin car dealer and mortgage broker -- was inspired by the sight of a grossly overloaded Lexus sedan exhibiting excessive rear wheel and tire camber. Instead of running vertically, the tops of the rear tires were tipped sharply inward. While most of us would have moved on to the next item in our daily routines, Scott was convinced there was something to be gained by orienting tires in this braced sea-leg manner. With his father's backing he sketched his Camber Tire idea and hired an attorney to conduct a patent search. In 1999, he was issued US Patent 5975176 for a "tire with a constantly decreasing diameter." Scott had invented the asymmetrical profile with an inner sidewall significantly shorter than the outer sidewall. While negative camber angles up to ten degrees might be beneficial, the first experimental tires Scott had made are molded with the tread angled two degrees.

In conjunction with a suspension adjusted to suit this radically different cross-section, Scott's Camber Tire delivers a long list of claimed benefits:

* Quieter running
* Reduced tread wear
* More predictable response during emergency maneuvers
* Increased track width
* Improved handling, braking, and high-speed stability
* Improved straight-line steering
* Superior performance during oval track racing

(See Scott's website, www.cambertire.com, for the patent disclosure and detailed list of performance claims.)

This sounds like too much to be true. The skeptic in us wondered why the major tire makers weren't on to this trick if it really paid such handsome dividends. There had to be a hitch. Driving on Camber Tires at the ragged limits of performance was the only way to see if they lived up to Scott's promises. When he offered that opportunity with some experimental tires manufactured by his initial partner M&H, we were the first independent organization to put Camber Tires to the test.

Before adjourning to the track, this primer might be useful. The phenomenon called camber thrust is what a leaning motorcycle uses to assume a curved path. Tipping the tops of both tires towards the center of a bend develops lateral forces at the two points where the bike's tire treads contact the pavement. These lateral forces, in combination with small steering angles, are what allows motorcycles to follow a curved cornering path.

Last edited by bagwell; 05-03-10 at 10:04 AM.
Old 05-03-10 | 09:12 AM
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If my memory serves me right, the factory tires on the Acura NSX were designed similar to this "cambered tire".

I believe they were thicker on the outside than on the inside, to create this camber effect.
Old 05-03-10 | 09:25 AM
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Originally Posted by Och
If my memory serves me right, the factory tires on the Acura NSX were designed similar to this "cambered tire".

I believe they were thicker on the outside than on the inside, to create this camber effect.
Not that I recall. I believe they were the same diameter all around. It was corner specific though. There was built it bias at each corner, but the shape was still a regular round tire.
Old 05-03-10 | 09:46 AM
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Reduced tread wear
I'm not sure I agree with that part of it. Ordinarily, in a straight line (which is the way a majority of everyday driving is done), negative camber like that will tend to cause more tread wear, feathering, and cupping on the inside of the tire. What it will do to the inside tires, while cornering, depends on a number of factors, based mostly on suspension design.

Last edited by mmarshall; 05-03-10 at 10:10 AM.
Old 05-03-10 | 10:07 AM
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Originally Posted by mmarshall
I'm not sure I agree with that part of it. Ordinarily, in a straight line (which is the way a majority of everyday driving is done), negative camber like that will tend to cause more tread wear, feathering, and cupping on the inside of the tire. What it will do to the inside tires, while cornering, depends on a number of factors, based mostly suspension design.
Only if your paradigm is both sidewalls are the same height.

This a variation on a theme. BF Goodrich used to make a directional autocross tire with stiffeners on one sidewall to essentially add camber where none existed allowing cars with fixed camber to get improved cornering traction.

The only downside to this design is camber is not constant on any suspension. It varies as the wheel position changes, and any car using a conical tire (which is what this really is) would need to have the suspension optimized to take advantage of this construction.

I doubt this will go any further than the tweel.

Old 05-03-10 | 10:26 AM
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Originally Posted by CK6Speed
Not that I recall. I believe they were the same diameter all around. It was corner specific though. There was built it bias at each corner, but the shape was still a regular round tire.
O.E. tire for the NSX was designed by Yokohama specificly for the NSX. I think it had a dual tread compound which lead to uneven tread wear resulting in tires wearing out in 8,000 - 12,000 miles. Honda had Yoko design a new tire with acceptable tread wear which became O.E. a year or two later. If only Lexus Relentless Pursuit of Perfection would include fixing the tire wear problem on the IS.
Old 05-03-10 | 11:48 AM
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Originally Posted by Byprodrive
O.E. tire for the NSX was designed by Yokohama specificly for the NSX. I think it had a dual tread compound which lead to uneven tread wear resulting in tires wearing out in 8,000 - 12,000 miles. Honda had Yoko design a new tire with acceptable tread wear which became O.E. a year or two later. If only Lexus Relentless Pursuit of Perfection would include fixing the tire wear problem on the IS.
I'm not quit sure about the compound contruction, but if I recall the cornet bias built in had the rear tires wanting to push in to aid the toe in alignment in the rear, and opposite for the front.

The quick tire wear was mostly due to the track car like alinfment with a lot of toe in on the rear. The class action lawsuit was for this reason, and on 93 or 94 Honda re worked the alignment specs to something more forgiving on the tires at a slight loss in overall performance and feel. Also I think the tread wear rating on the tires was like 140 or something. I still have a set with those tires at my dads house from my 92. While arguably a little outdated and unattractive, those 15/16 rims with those tires felt awesome to drive on.
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