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Tyre Sizes?

jdpef356

jdpef356

PCGB Member
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Hello, I'm in the need of some technical info hope someone can help.......I'm just about to purchase my first 911 (964) and I would like to possibly change the tyres when I get it. My questions is, what are the correct tyre sizes? The car has Cup 1 wheels and from some of my digging I believe that the front wheels originally should be 7" and the rears 9", this is where my knowledges endsThanks hope somebody knows!
regards
David
 
John, Cup 1 wheels on the 964 come in both 16" and 17" varieties so that will obviously impact tyre choice. The 16" wheels were originally from the 928 and were 6J (front) and 8J (rear) and were fitted with 205/55 and 225/50 tyres. The 17" Design 92 wheels were 7J (front) and 9J (rear) although there are also 8J Cup 1s around. Tyre sizes here were 205/50 and 255/40. Some people successfully run 225/45 on the fronts but it does depend greatly on the make of the tyre as many manufacturers specify a 7.5J minimum for 225/40 tyres. Hope that helps. Regards Dave
 
Like several other members I remain confused about the vexed question of tyre and wheel sizes for my 1992 911, 964, 2. So, yet again, ask for advice. I have 18" Turbo Twist, or Cup 3, wheels on my car as shown below and would like to swap them for 17" wheels and tyres. The details are:- Front Wheels & Tyres Dunlop 225/40 ZR18. Wheel offset 52mm (et 52) Rear Wheels & Tyres Dunlop 267/35 ZR18. Wheel offset 47mm (et 47) If I find someone who would like to swap, what tyre size and offset do I need to look for so that I know they will fit my car? I have not had the tyres off the rims, so do not know what are the rim widths of the wheels. Can these be determined by knowledge of the tyre sizes currently fitted? Johncolt.
 
This should have been in my previous post.
49B8974F4CEC49B6BE1DA56E84E887BB.jpg
 
Hi John You might want to edit your post.............has a mix of 17 and 18 in there. I'm guessing by the tyre sizes it should be 18?
 
Jon, the offsets you quote for the 17 inch turbo twists suggest that they are Mille miglia replicas. The widths of these are normally 7.5J and 9J respectively. Tyres for these are normally 205/50/17 and 255/40/17. There are a variety of 16 inch wheels that will fit. They are commonly 6J et 55 at the front and 8J et 55 at the rear and typically take tyres that are 205/55/16 and 225/50/16 respectively.
 
Thanks Ade and Steve. Just goes to show how confused I have become! I want to go from 18" down to 17". I don't know where I got 16" from. Johncolt
 
That makes more sense! [:D] Therefore you can put 17 inch replicas on which have the dimensions in my post above. Original 17 inch cup 1 and cup 2 wheels are 7j et 55 at the front and 9j et 55 at the rear. Also, a lot of 17 inch boxster wheels fit (see the ones on my car in my avatar). These are commonly 7J et 55 at the front and 8.5J et 50 at the rear. In all cases the tyre sizes are normally 205/50/17 at the front and 255/40/17 at the rear. Though you can often go up to 225/45/17 at the front if you want to decrease understeer.
 
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