Could some one please tell me what difference it makes putting the bigger wall tire up front on the new cars? does this soften the ride? I thought wall flex was a bad thing. I am upgrading from 225" X 15" all way round to 16" front and rears on my '86 N/A. I just got a set of 16" X 6" fronts and 16" X 7" rears with 205-45 up front and 225-40 rear.

This seems to be the standard configuration for them if not 205-45 and 225-50 setup. Should I purchase the same setup? or should i just go to a 225-40 all way round.

I am not sure what model porsche this came from (my guess an old boxster, they look brand new though). I need to look up the numbers i measured 40 offset at the rear and 50 offset at the font.

Also, can someone give me a heads-up as to what size spacers (or spacers with studs) I would need.

I have read so many threads on spacers my head is spinning.
I have a 1986 n/a with the stock spindles.

Current Setup:
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Front - 15x7" offset (23.3mm)
Rear - 15x7" offset (23.3mm)

New Setup:
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Front - 16x6" offset (50mm) "996.362.112.00"
Rear - 16x7" offset (40mm) "996.362.114.00"

Differance in Front is (50mm - 23.3mm) = 26.7mm

Differance in Rear is (40mm - 23.3mm) = 16.7mm

So beeing an inch smaller in front i gain an extra 25mm but it only adds 12.5mm to the backspacing and not just to the offset?? Right.

This is where i get lost

I need to make 100% sure that the new rims are indeed 50 front and 40 rear offset.

My head hurts i am going to lay down now.

 

The profile measurement on your tire is a percentage of the width. A 205-40 is going to have a lower profile than a 225-40, so you'd get 205-45 up front.

 

Learning something new every day, thanks qoncept944.

 

"So beeing an inch smaller in front i gain an extra 25mm but it only adds 12.5mm to the backspacing and not just to the offset?? Right."

Huh? Why are you downgrading rim widths? The 944 has such great balance at 50/50 weight distribution, best performance is with identical tires & rims front & rear.

In that new configuration, you'll actually be moving the outside rim-edge 1.5" inwards. About 1.0" is due to the increase in offset, then push in another 0.5" for the decrease in width. It's gonna look really narrow.

Also the proper tire-diameter for this car is around 24.87" which comes out to a 205/55-16 front and 225/50-16 rear tire.

In 17" wheels, you're looking at 225/45-17 and 255/40-17 tires.

 

 

hmm.. so what size spacers would I need back and front? I looked and they are indeed 50 front and 40 rear offset.