Heat cycled out tires - Any visual clues?

[ABenLauda]

Sorry for the noob question, but are there any visual clues to heat cycled out tires?

These are my rear RE71Rs after ~ 35 heat cycles. Grip has reduced on track, but they aren't undrivable. I just wanted to confirm if it's time to toss 'em.

TIA.

[sc_tr0jan_m3]

Those look totally normal and prolly have more life left than you think.

Usually you'll see a blue shimmery texture on the outside if you're really pushing the tire. But normally I just look for uneven wear from the inside to the outside of the tire.

[Suds]

I’d flip them on the rim and wear out the other shoulder.

[NYG]

No.

There will be no visual indicator that a tire has given up. It's on an atomic level - some of the polymers become permanently deformed in scattered areas around the tread every heat cycle. They won't go from grip to no-grip at some specific heat cycle. You'll feel it on the track if you pay attention to it. Gradual increase of slip/skid in brake zones, more noise/slip in corners, more oversteer/understeer, harder to keep on race line, etc.

35 heat cycles on RE71R means your grip has dropped off by a huge margin.

[robbo mcs]

If you see a bluish purple tinge to the rubber, especially on the edges they have been overheated and are toast.

If they have been well looked after, but have done a lot of heat cycles, it can be hard to tell by just looking at them.

You can get durometers that measure the hardness of the tire, which can be useful. A rough guide is sticking your fingernail in, and comparing that to a fresh one.

The most important question is what you want to do with the tyres. If you are super competitive and trying to set the fastest times, then tires that have had too many heat cycles will cost you a lot. If you are doing fun days, non-timed days, learning etc, then there is no harm in using them, they will be slower and have less grip, but are not dangerous per se

[FMLYSDN]

RE71Rs can be run down to the cord. Your tires have plenty of life in them. Obviously the performance will drop from brand new, but as stated here, your not setting any pole positions. Rotate them to get even wear. You can run reverse tread in the dry, just make sure you run the right rotation in the wet though.