Upgrading wheels

I was thinking of upgrading the wheels on my 92 C2. Currently, it has 16 inch Cup wheels, 205's in front, 225's in the rear. I was considering going to 17 inch wheels, 225's front, 255's rear.

My main goal is to increase traction, especially in the rear, and I'm willing to sacrifice some ride quality to accomplish that.

Numerous questions:

1. What advantage is there to going from 16 inch to 17 inch wheels?

2. Do I need to have my speedometer recalibrated if I increase the wheel size? If so, I suppose I just take it to my P-mechanic?

3. Does anyone have any specific tire width recommendations? I chose 225 and 255 because they sound about right, but does anyone have any particular suggestions? I'd like to go as wide as possible to give extra traction, especially in the rear.

Thanks for any help.

1: Shorter sidewall, so less flex, so crisper handling.

2: You reduce the percentage height of the wheels. If you have 225/50-16 now, you use a tire size calculator to find the comparable size for 255. Here's a calculator. The best size for a 255 would be 255/40-17.

3: Tire width depends on the width of the new wheels you choose. It also depends on what you can fit under your fenders, even after curling the lips.

Good luck.

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Jack Olsen
1973 911 T sunroof coupe

[This message has been edited by JackOlsen (edited 10-16-2000).]

If you have 205/55x16 and 225/50x16 now you can replace them with 225/45x17 (634 mm) and 255/40x17 (636 mm)without recalibrating speedometer. These 17 inch sizes are only slightly larger in overall diameter (632 mm current tires). Make sure you put them on 7.5x17 and 9x17 wheels (if you settle for cup style rims). Also be sure that you get the correct offset.

Drew, I upgraded to 17" Fikse fm-10, 8.5 front w/ 235/40/ and 9.5 rear w/ 255/40 yoko A032R. We tried this combo to be sure it all fit under the fenders, looks like I could go wider especially with the yokos, don't yet know about other brands of tires though. Don't know the offset (big fikse secret)