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, Wed, 30 Oct 2002 15:58:11
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GM is right, SPG wheels are 5.5".
The widest section width approved for use on a 5.5" wheel is 205. Bear in mind though that a 205/60 is the wrong tire for your car--it is too tall. The correct aspect ratio for a 205 is 55 which will be slightly shorter than the stock size of 195/60. On measured rim width the sidewall heights are as follows:
195/60 - 117mm
205/55 - 112.75mm
205/60 - 123mm
Bear in mind that the measurement wheel width for a 195/60-15 is 6". That means that on a 5.5" wide wheel, the section is actually about 2/10" (about 5mm) narrower and the sidewall is slightly taller.
For a 205/55-15 the measured wheel width is 6.5". Thus, on a 5.5" wheel the section width will actually be about 4/10" (about 10 mm) narrower and even a bit taller. So, a 205 will actually pick you up a contact patch only about 5 mm wider (not the full 10 mm) on a 5.5" rim.
Also, the difference in sidewall height will a bit less than the sidewall height difference noted on the measured rim width (117-112.75 = 4.25 difference). The true difference in sidewall height will be in the 2.5 - 3mm range which means the 205/55s will have a total height of less than 6mm shorter than the factory size of 195/60.
All that being said, I like the 15" SPG wheels and run those on my car. I just hate the way they are tucked so far in the fender (especially the rear), so I run spacers (here is my one comprimise of a small amount of performance for looks since the spacers add a very small amount of unsprung weight).
I personally like the 205/55-15s, not for the extra 5mm contact patch, but because no really good tires are available in 195/60. In 205/55-15 you can get Bridgestone S-03 tires which are always near the top in performance tire evaluations and are one truly sticky tire. If you're more budget minded, you can get the Kuhmo ECSTAs for less than 3/4 of the price and they are still very good (as well as some other tire choices).
One more point while I'm on a role, the rice boy mentality that bigger is better as far as wheel size is concerned, is dead wrong. Something like a 225/35 will handle worse than a 225/45.
I've seen several tests of this and I can't remember who it was, but a major magazine did a really good test where they took a car which came stock with something like 195/55-15s on it and put the exact same tire on the car but in different wheel sizes. I believe the test sizes were something like 205/50-15, 205/45-16, 205/40-17. The 17" wheel performed the worst and the 16 performed the best. Moral of the story--bigger is not always better. Extremely short sidewalls do not perform well. If you are running 18" wheels and maybe even 17" on a c900, you are running a very short sidewall and are doing so for looks not performance.
Dave D
90 SPG
posted by 63.78.1...
, Wed, 30 Oct 2002 15:58:11
, Thu, 31 Oct 2002 08:54:47, Wed, 30 Oct 2002 22:46:03
, Tue, 5 Nov 2002 16:10:20, Wed, 30 Oct 2002 16:05:15
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