I bought wheels and Kuhmo mx tires from Tirerack for open track use on my MCS. In my last open track I noticed that the tires seem to have given up a lot of grip. There is still about 1/4" of tread left. They have seen about 25 sessions and typically are about 175 degrees f in the front after a session. They get rotated front to rear between events. Do street lose performance after to many heat cycles or should I look for something else?

 

Hayseed,

Yes, you are correct. All rubber gains firmness, and looses compliancy from heat cycling. Its rather common for those who run Hoosiers to opt out of tires, before they have reached 2/32nds - bear in mind an R3S03 is new at 4/32nds.

Heat cycles help new fully treaded tires gain more tread block stability, and less squirm.

This also explains why even if your Michelin X One tire have 40k on them, and pleanty of tread, but lack the grip they once had. You had them for 10 years - plenty of heat cycles later, no more compliancy - hence no more traction.

I wold not change unless you were unsatified with 1st 20 session's performance.

Alex