Hicompression

I am running 20" rims on my 2006 Mustang GT. What is the best tire pressure to run with Sumitomo HTR ZII 255/35ZR20 tires all the way around?

Jazzer The Cat

The recommended pressure ratings will be on the side of the tire.

I would put adjust the pressure to be 4 PSI below the middle range of tire. That is to say if the tire says 36~44 PSI, the middle range would be 40 PSI. The tires will generally pick up about 4~6 PSI when warm, so start with 36 and see what how your ride responds.

Running a 255/35/20", you are not going to have a lot of "volume" of air in the tires. You need to pay pretty close attention to the pressure level as a small leak can have a relatively large effect on how they ride/handle/wear.

HTH

Jazzer

Hicompression

The tires have a max rating of 51 PSI (no range stated on the sidewall). I have the tires aired up to 38 PSI currently. Factory requirement for my old 17's was 32 PSI.

Jazzer The Cat

51 PSI is quite a way up there, but likely due to the reasons I mentioned above. 38 is going to be a OK place to start when tires are cold. Drive it around for a while and check the pressure after an hour or two of highway driving. See what pressure they are once all heated up. I am curious how much they will rise being such a low volume tire, for lack of a better word.

Jazzer

colin@tirerack

A 255/35-20 Z3 is rated for 1609 lbs at 42 psi. Your stock size is rated for 1587 lbs at 32 psi. Using a range of upper 30's to lower 40's would be fine. You will have to play with the pressure a little bit to see what will give you the best ride and handling.

Stoenr

Cmon Jazz, of all people I thought you would know the sidewall pressure is only the tires Max inflation, and not a recommendation!

I would be running those 20's at 42 if it was me. One small pot hole or curb could ruin the wheels if you run too low.

Jazzer The Cat

Your right.... what the hell was I thinkin'?

Jazzer

Hicompression

Thanks!