dpaul

We purchased a 2017 Cayman and ordered the 18" Boxster wheels. After a few weeks, I noticed that the front wheels are convex and the rears are concave. Any idea on why they did not make them the same? Either both concave or both convex?

Just curious...

Macster

Pics would be nice to show exactly what you are referring to.

dpaul

Overall view... the difference is slightly noticeable in this view
Next is the concave rear
Then the convex
This is NOT a political post... please ignore the banner on the wall if you are offended. I will not argue politics as I believe that movie stars/athletes/musicians should not either!

Bill Lehman

It's difficult to see in the photos but all Cayman and Boxster wheels have a different offset (difference between the centerline of the wheel and the hub) between the front and the rear. Consequently the wheels have a slightly different appearance.

danschy

Also the rear wheels are likely wider, which would push out the rim relative to the center. But I'll have to admit, I've never noticed that before and will have to check mine.

DBH

I have a 2015 CGTS with 20 inch Carrera S wheels with a similar concave/convex configuration. Not being an engineer/tech person my simplified explanation would be to accommodate the suspension setup and the different tire sizes and wheel rim widths front vs back.

dpaul

I have eliminated the front calipers as being a reason for the rim difference. I thought the larger front brakes may have larger calipers and needed more room...nope!
The distance from the front rotor to the outermost surface of the caliper is 2 1/16' and the rear is 1 31/32" (That's 52.5 & 50.0 mm for those who use the horrid metric system).
If the front rims were concave, I believe that the rim would interfere with the brake caliper. If the rear rims were convex, the aesthetics with the amount of spacing between the caliper and the rim spoke may have too much room for the Porsche designers...?
Eventually I will swap the front and rear rims (without driving of course) and see if that sheds any light into this quandary.

danschy

Yep, never noticed it before, but my 07 Cayman with 17" wheels has the same convex/concave "issue".