I am in my second season of Autocross on 17" Kuhmo XS tires. I'm guessing with competion and schools I've put about 150 runs/cycles on them. I am not at the wear bars.
I am NOT a great autocrosser, but I think I've noticed a huge loss of wet traction over the life of these tires so far. I'm not just talking about puddles, but just wet pavement. In two consecutive days of competition, the dry day I was 1/2 second off the pace and on the wet day I dropped 6 seconds off the leaders.
I am frustrated and may just be looking to blame something other than the driver. It could just be my wet day driving technique, but I wondered if summer tires (wear rating 180) loose traction after a certain number of cycles?

 

Take heart! They definitely do...

I run a new set every season for that reason.

Cheers,

Charlie

 

Wet performance definitely drops as a tire wears.

 

...and the rubber hardens over successive heat cycles...

 

... and that is something I did not know

 

According to Tire Rack's comparison test, while competitive in the dry, the XS did very poorly in the wet compared to RE-11, Star Spec, and AD08. Thus, they're not a good EP tire choice for wet conditions even when new.

I'm not yet convinced that street tires (even EP tires) heat-cycle out in the same way that R-comps do (especially autocrossing), but the tread wears down (reducing water evacuation), and the rubber tends to harden with age and weathering. The aging/hardening should affect grip in the dry as well as the wet.

You have our permission to get new tires.

 

Will you be able to provide me with a new excuse for not finishing better???

 

"I forgot to put it in Sport Mode all day. I kept wondering why it felt so strange."

I can use that one over and over because I'm 73. If you're a lot younger, you should use it just once.

 

Err...

Here are a couple of my latest excuses:
1. my new R1Rs delaminated, so I had to reduce slip angles...
2. my rims aren't wide enough for the tires, resulting in deformation of the contact patch...

Of course if we find autocross too humbling, there is always golf - I sometimes watch the pros and obviously that's a really easy game!

 

Ha LMAO