devenh

I compete in the Silver State Classic Challenge which is an open road race held on a 90 mile stretch of highway in Nevada. The Chief Tech strongly suggests not using tires that have seen track use because of the increased likelihood of tire failure due to numerous heat cycles.

Do you agree with this? If so, above what sustained speed would you be concerned?

JCP911S

Depends on the tire. Most "R"-type track tires require 1 heat cycle to reach optimum performance, but will deteriorate with use. "Numerous" is vague... is that two or twenty? Not sure that is relevant, though.

Tires have maximum speed ratings set by the manufacturer. There is a letter code used... it is on the sidewall, and certainly in the specs. I don't have it handy, but you can find it on the web.

If you are doing this, determine the maximum sustained speed of your car and make sure you use a tire with a higher speed rating.

JCP911S

Tire Rack has a good discussion of this on their web site.

Matt Romanowski

You didn't give much info. What tires? What car? What speeds?

I've never heard of a heat cycled tire being more likely to fail.

jdistefa

Unless the tire is old, heat cycled, cold cycled, close to corded or otherwise abused, I'd guess this 'advice' is complete hooey. Never heard of such a thing.

philstireservice

The number and the letter are called the load index and speed rating. Very important to make sure the tire can carry the weight of the car.

At event like this I would suggest a new set of tires. An initial heat cycle would be an excellent idea on a new set of tires.

devenh

The car is a 991 GT3 with either OEM Dunlap or Michelin tires (don't have the car yet). In my class, the race is 90 miles at an average speed of 130mph. There will likely be 10 mile sections driven at 145mph.

These speeds are well within the Y ratings (186mph) of the tires. The Chief Tech's advice was based on an apparent correlation between tire failures and prior track use. When I see him in May I will press for more details.

jscott82

I think I would be more concerned about fragilness of slicks on an unswept road.

Frank 993 C4S

Germans drive high speeds on regular street tires on the Autobahn every single day. Make sure you have the right load and speed rating and that they are properly inflated. I wouldn't bother with slicks.

devenh

Yes, street tires definitely.

jerome951

Honestly, I'd put my trust in a set of tires that has proven itself at high speeds a few times over a fresh set.
At the speeds you described, I wouldn't be overly concerned. Just my $0.02.

Matt Romanowski

I wouldn't worry about the factory street tires for those speeds. Like others said, these cars do well above that speed on the Autobahn everyday.

DTMiller

I'm confused by the highlighted part in the second quote. I'm having touble reconciling never having heard of such a thing when the list includes "heat cycled" as a reason why tires might be bad. Can someone clear this up for me?

Related question -- at what point, if any, do heat cycled tires like Toyo RA1s drop in performance below something like a Michelin PS2? Also, obligatory:

Steve113

Love that graph

Dr.Bill

Sounds like the last time I drove to Vegas. No problem.