Whats the preferred tire size for the 17" Cayman split 5 spoke wheels on a 986? Doesn't appear that I can run 225/45-17 fronts and 255/40-17 rears like I am now on my 7"fr/8.5"r Boxster wheels. Any suggestions to keep things kosher? These are my street wheels.

 

No one has any experience on running 225/45-17 on a 17x6.5 and 255/40-17 on a 17x8?

 

Here is what I believe to be true. You might ask Damon at Tirerack. This list doesn't go below 8' but as you can see a 255 will just fit on an 8.5" And doing the math it appears the 225 is a little too wide for a 6.5. Even if it holds air I don't know that I would try it.

Here are the legitimate size ranges of tires that you can fit on different width wheels:

8": 215-245
8.5": 225-255
9": 235-275
9.5": 255-285
10": 265- 295

 

I was wrong. According to this they will fit. Plug in your infor and it will calculte everything for you

http://www.rimsntires.com/specs.jsp

 

Good tire manufactures websites list approved wheel widths for the tires they make.