Just purchased a set of 18' 993 turbo wheels for the track. I am running 225 up front and 275 on the rear. When I installed the rear wheel, I noticed the inside of the rim was making contact with the lower portion of the spring perch. I'm not certain what the offset of the rim is, however it is more than the factory setup. When viewing GMP performance website, they're showing a cayman with the same wheels and 295 on the rear. I cannot see how these fit. I believe that car has 5mm spacers but I don't think that is enough tomake them clear. I'm supposed to be running these on the track this coming weekend.Please help. Thanx.

Higher offset of course will bring the wheel closer to the shocks, so the only way would be to run spacers. The spring perches slope upward and as you push the wheel outward, the clearence would get better. Depending on how much they touch (I assume you are running 275/40 tires) either a 5 or 10 mm spacer should do. Or possibly a 275/35 + 5mm spacer.


I of course do not know how much track experience you have, but I suspect you will not be too happy with your tire choices. I cannot say this for sure, but from my street driving the Cayman needs more tire up front then the rear, already has mild to moderate understeer, I think you are exagerating the situation. I might of course be completely wrong, so do let us know what you think of the setup please.


Cheers,

Edited by - FT on 02/26/2006 7:02:18 PM

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FT

go to GMP website contact info and call Stephen at GMP. That was my cayman and they worked out the fitment over the course of 2 days. The pictures on their website show after lowering an inch and not sure if they had spacers in on those or not, but my stock wheels have 15mm spacers. good luck.

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My Cayman may be gone...but not forgotten.

The Cayman 18 inch wheels are made by Ronal.Ronal USA provides general information about wheels here:


http://www.ronalusa.com/shopping/index.html

Is it just me or does it seems like most wheels on the market just don’t fit on our CS. Is this because of the wheel bolt pattern or the offset or both? I know there are other factors that go into determining whether or not a wheel will fit your car (besides the obvious diameter and width) like hub height, caliper profile and hub diameter. Is there anybody out there very knowledgeable about Porsche wheel requirements and what’s the primary reason most wheels don’t clear manufacturer specs for vehicle fitment.
It’s been very frustrating for me because I’ve been dying to put some custom wheels on my CS and none of the wheels I like fit and these are from reputable manufacturers like O.Z. Racing etc… I just can’t justify spending well over $3000 for a set of wheels just for the sake of buying custom wheels if I’m not in love with the look and quality of the wheel. BBS and some of those other brands are ok but they just don’t get my juices flowing.
I know the difference btwn a front drive and a rear drive wheel. The ones I’m looking at are fitted for M3, M Coupe, Mercedes, Ferrari etc.. but no Porsche sizes????
If this is a Bolt Pattern issue, does anyone know where I can get a quality wheel adapter that will work on my CS to convert the bolt pattern to a more conventional pattern?
If there is any help out there, I’d really really appreciate it. Thanks in advance.

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You can't make anything fool-proof... The fools are too inventive!

I kinda like the looks of these. A couple of the forum sponsers sell them.

Troy Have you checked out Tire Rack they have a good selection of wheels that fit Caymans, including the great O.Z.s and their website lets you see the wheel on your car ! I know firsthand they are one of the best companies to deal with. Extremely knowlegable about any wheel or tire question you might have.

Rebel: I agree with FT about your new front/rear tire width stagger, but realize that size choice was probably constrained by those offered by the tire brand you want to run. There do seem to be several brands offering the 245 and 275 sizes, however.

Troy: Pick any car you want, and you'll find that most aftermarket wheels offered won't fit it. So it's not just CS owners who are constrained in their aftermarket wheel choices. The Porsche wheel bolt pattern is 5-130, but it's mostly the offsets that restrict our choices. If the offsets of an aftermarket wheel are greater than needed, spacers of various widths are available. If the offsets are not enough, however, there are no negative width spacers.