Thread: Blown Fuchs?
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Noah930 Noah930 is offline
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Join Date: May 2005
Location: Los Angeles
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Originally Posted by GO DAWG GO View Post
Andy and Noah,

I agree, but Porsche is the only company that I know of that sells a car with different width rims front to back. Lets say I bought 11.5 x 17's, I would have a much better selection of tires...Yes/no would a 17 on the rear look funky with a 16 on the front...???? Am I out of my mind? As I said Andy, I think some RSRs had a larger diameter wheel in back....Set me straight!

Porsche's use of varying width rims front and rear on the 911 was intended to address the extreme rear-weight bias of the car. Wider tires at the rear to handle the extra weight at the rear. I believe that the engineers had wanted to do so for quite some time, but were held back from doing so due to various countries' DOTs specifying that for a road car, the (usually one) spare tire had to be able to be used on both front and rear applications. It wasn't until the advent of the space saver spare that one spare wheel/tire was able to substitute for both front and rear applications. Then, Porsche was freed to use wider rims in the rear.

All road cars came with same diameter rims front and rear. But the 935 had smaller 16" diameter rims in front, and larger 20" rims in the rear. Group 5 rules dictated that the tire/wheel be no wider than 16". That meant a 15" wide rim, plus whatever else came from the tire sidewall. That was insufficient traction at the driving rear wheels of the 935. So, to get a bigger contact patch, Porsche decided to go with a larger diameter rim (20"), so that if the contact patch couldn't get wider, then it would get longer (fore and aft), to increase the overall area of the contact patch. No need for such extreme grip at the front (plus the need for the aerodynamic slantnose fenders), so smaller diamter rims of 16" were run in the front.
1987 Venetian Blue (looks like grey) 930 Coupe
1990 Black 964 C2 Targa
Old 03-05-2008, 09:44 PM
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