legokcen

Got a question.

Don't know if this should go to the tech forum, but here it goes.

As a tire ages, does the overall grip deteriorate as well? If so, how much? The reason I ask is, My original donlops still have great grip after 4 autocrosses and 12K miles of spirited driving.

For sake of the following assumption being valid, I'm only talking about dry conditions. I know bald tires have very poor wet traction:

Tire Grip is gotten from the contact patches on the tire, so even as the tire ages and wears, the contact patches remain pretty much the same surface area. Does this mean that the traction (again, dry) remains pretty much the same for softer compound tires as the tread depth decreases? Does the rubber compound get harder as the thread wears, therefor making the tire less "sticky"?

Anyone out there have any data on dry traction vs traad depth?

Thanks in advance.

ezrider55

Racers shave their tiers before use.

legokcen

I have also seen this. What is the benefit of it?

Ophitoxaemia

a tire will lose traction as it ages because of the effect called 'heat cycling'. each time the tire is heated and cools (for example driving on the freeway, then stopping, or racing) the rubber hardens a little bit. harder rubber has less traction.

note that 'heat cycling' is also a positive thing racers do to their tires- one initial heat cycle before the tire is raced has stabilize the rubber and make the tire have more consistent traction through its life.

street tires are designed to be hard enough to start with that they dont change too much before the rubber is worn off. race tires like i use for autocross may very well get hard and slow before the rubber wears off. my kumho ecsta V700 r compund tires start to get a little slower after 50 runs, but there is still lots of rubber. they will eventually return less traction than street tires.

shaving race tires doesnt have to do with the hardness of the rubber or wear- it simply reduces the height of the tread blocks and so reduces the slip angle of the tire. it also makes the tire slightly lighter and smaller.

james

GeorgeH

iTrader: (2)

What Oph* said, although some tires are more prone to hardening than others. On my Miata, my T1-S tires lost allot of grip when they were worn down to the wear bars. My Falken Azenis, on the other hand, showed no signs of giving up when worn similarly. So it just depends.

Mitch Strickler

I read a detailed explanation of Bridgestone design to reduce performance loss with use on the RE040, but the emphasis was more on wet traction than dry. The tire material is layered (not a technical description; I don't mean there are bands of rubber) so that the tread that hits the road when the tire is half worn has better wet traction than it would in a conventional tire. I'm not a tire expert, so I can neither explain the design in more detail, nor vouch for its effectiveness.
Mitch

B-Nez

I believe the S-02 Pole Positions have the multi-layer compounds. That was why they were my 1st choice, but they were on factory back order...

rx8cited

Here you go, right from the experts:

"....tires typically provide their worst wet traction ... and their best dry performance just before they wear out."

"It is also important to note that your old tires probably had very little tread depth remaining when you felt it was time to replace them. As any autocrosser or racer who has tread rubber shaved off of his tires will tell you "low tread depth tires respond quicker.""

This seems to agree with what you're experiencing so far, and your tires' dry handling should get better or no worse just before they wear out - something to look forward to .

rx8cited