What would be a good tire pressure for 205/40/17 wheels for increased gas mileage and not risking cracking the rims?

 

I run 42psi on the same size tires. I blew a sidewall out last year at 35psi on a bump, so now I make em as stiff as I can.

 

are u running 42 psi on all tires? or does it depend on wat springs and shock setup u got also? i am asking this because i too also blew a tire wall at 32 psi.....should the front and backs be different psi? cuz i know peepz that keep the same all around...

 

42 on all, and it has nothing to do with gas mileage, shocks, or springs. With the stock tires you should go with what is printed on the drivers door which is less than 30. Aftermarket with the thin sidewalls (40) need to be harder so they dont flex too much and blow out the sidewall, like what has happened to both of us. The only thing that could happen with the tires all being the same psi is the fronts may wear faster than the rears if you dont rotate them. Accelerated wear is the lesser of two evils than blown sidewalls.

 

You guys should talk to one of the big tire stores, like Tire Rack.
There is a calculated amount to increase the stock settings for each size over stock you go. I can't remember it but 14" wheel to 15: was like 4 more pounds.
The reason there is less air in the rear is simply less weight on the tire. Tire pressures are based on vehicle wheight and tire/wheel size.