AustinSedz

Hey there,

I've been googling and searching the forums for references and trying to find a calculator or formula to follow.

I recently replaced my wheels on my 987 cayman with wider wheels are tires, and am unsure of the correct pressures to run for the street.

OEM is

235/40/18 on 18x8 recommended 30psi
265/40/18 on 18x9 recommended 31psi

I've switched to:

255/35/18 on 18x9
285/35/18 on 18x10.

Can anyone advise on the correct pressure to run for the street? Want to try to maximize my street wear so I get more out of the tires at the track

Ubermensch

Just stick with the stock pressures. 1-2 psi here or there isn't going to make a major difference when it comes to street wear.

extanker

^^^^ this

JCtx

I believe Porsche recommends the same pressures on any wheel sizes available. Tire widths are always the same (235/265), but profile changes from 45 on 18s to 35 on 20s. By the same token, a little wider width shouldn't make any difference. The car's weight is what makes a difference. Also remember Porsche has 2 different pressures: one for 'comfort', and the other for more aggressive driving, I guess. But I find that last one excessive at 33 all around, for a 3K+ lb car. When hot, they go well beyond the 35 hot I like, so I always keep pressures at the 30 cold comfort setting (and set TPMS accordingly). Experiment to see where you like them.