[BrettKA7]

I had these tires installed June 2020. The tire code on the side of the tire says it was manufactured in 2019.

Do these cracks look normal? I thought these only happen when tires dry rot, but maybe it has something to do with the soft, sticky compound?

Also, since we are on the subject. Does the factory recommendation of 39 PSI in the rear tires seem excessive? I know the F22 and F82 owners who track their cars tend to shoot for 40 PSI or so hot. 39 PSI cold puts me at 42 PSI hot usually. I tend to drive spirited when it's safe to do so, I'm wondering if something more like 37 PSI might be better.

[ggggbmw]

Have you been somewhere really cold lately? Where the tires would have gotten below 20F? With a Huntington Beach location, I'm guessing you wouldn't be that cold.

Usually cold damage cracks are fewer and deeper, and run in longer arcs. So probably not.

It doesn't quite look like the 'melt' creep from track/auto-cross driving either. The top edge looks like that a bit, but you can see some small cracks in the grooves which doesn't match that.

'Dry rot' cracks are usually more in the sidewall flex area.

In any case, it doesn't look like the cracks are deep enough to be a concern.

[dradernh]

Originally Posted by BrettKA7

Does the factory recommendation of 39 PSI in the rear tires seem excessive? I know the F22 and F82 owners who track their cars tend to shoot for 40 PSI or so hot. 39 PSI cold puts me at 42 PSI hot usually. I tend to drive spirited when it's safe to do so, I'm wondering if something more like 37 PSI might be better.

The best way to find out is to try 37 hot and see how you like it. Drivers frequently have different preferences when it comes to tire pressures for street driving.

[overcoil]

Those shoulders look like normal wear from aggressive fast cornering.
How many miles are on the tires ?

[XutvJet]

It's normal. That type of wear is more from abrasion.

I routinely run 32-34 psi cold with these tires. I've done so with the stock Super Sports and now with the replacement 4S. I haven't had any issues running the PSI at this level for over 5 years.

[Miata13]

Originally Posted by XutvJet

It's normal. That type of wear is more from abrasion.

I routinely run 32-34 psi cold with these tires. I've done so with the stock Super Sports and now with the replacement 4S. I haven't had any issues running the PSI at this level for over 5 years.

I did my first auto-x last weekend on the o.e. Super Sports. It was a cold start to the day at 42 degrees warming to about 52 in the afternoon. Found fronts needed 4-6 lbs more pressure over the o.e. spec 32 lbs.(as they were rolling over a bit much to the sidewalls); rears seemed fine at o.e. spec 36 lbs.

Anyone else have t.p. recommendations for the MPSS o.e. tires?

[TrboMike]

Looks like normal surface cracks from aggressive driving to me.

I'd stop using tire shine. Some of the cheapo ones or if you overdo it or apply it during too hot of a day can also hurt the rubber.