I have 235/40/18 S0-3 tires on 18" SSR Comps

what tire pressure should i run? I'm currently at 42psi upfront and 40psi in the rear.

BTW, whats a good time to take off summer tire for the stockers?

 

i was looking for something less obvious and more along the lines of a temperature where the summer tires don't function properly and degrade the performance of the tires and of the vechle as a whole.

 

Your air pressures seem ideal. You can play with the rear pressure to try and control understeer, but you've got the right idea.

Summer tires, I've found, can't be depended upon below about 40 degrees. However, when they heat up after a few miles, they work well again. I change mine at the first real prediction of snow. I tend to hold out as long as possible.