Track day tire wear and cold tracks.

[Ben Peeples]

I have three questions. David mentioned that he had been taking a densitometer (sp) to the track. I have been changing out the track tires with a fair amount of tread left because they seemed to not as stickly after several days. Are sticky and hardness related? ( Hey in the South we are all cousins. ) Is softness more important that stickiness? How much does a densitometer cost and where do you get one? Ben.t

[JoeV]

Let me start by apologize because I don't have the answers to your questions. However I do have something to add to the discusion regarding track day tire wear.

 

I've recently learned two very intersting things about performance motorcycle tires and thougth I'd share it here.

 

#1 - Street tires can be stickier on the street than racing tires.

Sticky track tires need to get hot to work at their peak performance. Sticky track tires when used on the street don't often reach peak performance temps and can actually be less sticky than performance tires designed for "Street" use.

 

#2 - Tread depth alone does not indicate tire life. Tires have a limited number of heat and cool cycle. After they have gone through a number of heating and cooling cycles, even if they have good tread left, they may not get as sticky when they heat up.

[Gleno]

 

 

That was 4 questions.

[Ben Peeples]

Joe V,

I have often heard #1, but it is not my experience. My cold track tires feel much stickier than my warm street tires.

Gleno,

It was 4. How about 4 answers. Thanks, Ben.

[Rocket_Cowboy]

From my understanding hard tires are usually not as "sticky" as soft tires. That's why in racing, the tire gamble is whether to go softer for best grip, but then softer tires don't last as long. Racers will go with a harder tire for longevity, and balance the need for grip versus longevity when making tire choices for a particular track.

 

Tires will have an optimum temperature at which the operate, similar to brakes. Using race tires or brakes on street conditions is likely to be suboptimal, because the components are not likely to get up to or stay in their optimum temperature. Race tires might feel more sticky than street tires even when cold, but that could also be just the difference between soft and hard ... not an example of optimal grip.

 

Heat cycles ... soft tires will start to get hard after some number of heat cycles. I've seen some track tires with plenty of tread left, but the tires had blue'ed so much from the heat cycles ... they were hard as concrete. At that point, there wasn't much grip left at all.

 

Hmm ... the 4th question ... I don't remember what it was.

[Ponderosa]

Generally speaking the softer the tire the better traction it has but design and compounding play a big part in tire performance. To measure the hardness or a tire you need a Shore durometer. Google it and you can find one for tires as there are many scales to measure hardness of different materials.