rexpontius

Dear All,

I just bought a very nice set of original Porsche CUP II wheels for a steal price of 200 EURO including a set of Michelin tires with full 8mm profile.

The wheels are 7x17 ET 55 at the front and 9x17 ET70 at the rear.
Tire sizes are 205/50/17 and 255/40/17

Currently I have a set of Mille Miglia Cup 2 replica wheels on the car (I think they are 7.5x17 ET 52 or 55) with 235x45x17 tires, with the factory S3/86.5 spacer at the rear.

I think the new 9x17 ET70 wheels will fit good/perfect in combination with the factory spacer, and the tire size should work as well.

For the front, I am a bit in doubt what should work best. The 7.5x17 (replicas) or the 7x17 originals. I think the 7x17 might be a bit on the 'skinny' side, at least with 205x50x17 tires on them.

Would it be possible to put 225x45x17 tires on them?

What is your advice.

Many thanks
Cheers

Hilton

No issues putting 225 wide on 7Jx17 rims. As for your choice - I'd go with the highest front offsets of your wheel sets. ET55 just about works on the later suspension style which you have, as all RoW 86's have the later suspension/brakes (86.5 is a North America only thing).

I ran 225x45x17 on 7Jx17 ET55 Boxster wheels on my old S4. I prefer the feel of higher offsets, but they were a lot better than the ET50 ones I had before that.

My advice is, for later suspension/brakes, treat ET55 as the minimum, and the higher the better up to stock ET65. For early cars, the suspension geometry is slightly different, and ET50 is about the minimum, although again, the higher the better. (My idea of "minimum" is based on preserving at least some of the negative scrub radius designed into the 928 suspension geometry - once its eliminated, it actively makes the car unstable)

rexpontius

Thanks, my car is a USA imported 86.5 (with s4 brakes, suspension, etc) I will check which wheels have the best offsets

redpathtribe

I would just run the new OEM Cup II's with the good Michelins on them, then when the fronts wear out, replace them with 225's. Not sure I'd mix the OEM Cup II's and the replicas. It may not really matter, but they probably differ quite a bit in weight. The OEM's should be lighter and stronger than the replicas.

You may not realize what a bargain you actually got. Those 9x17 et70 wheels are VERY rare, at least is the US, and quite coveted by some (like me!). You can run those on the front of your car with that (correct) offset. What I would really do if I had them is look for a pair of the more standard rear 9x17 et55 Cup II's, and then run the 9" wheels on all four corners. Handling would be great!

rexpontius

Yesterday I mounted the OEM cup IIs on my car and also measured the weight difference. The Mille miglia's weighed 23 kg's incl tire, the 7x17 OEM's weighed just 19 kg's incl tire!

Even the wide 9x17 oem wheel was 1kg lighter.

The effect on driving is amazing, the car does not tramline anymore!
The ET value of the OEM wheels is just 3mm different (52 vs 55), but it makes all the difference!

Only thing I want to change is the rear spacer, even with the 21mm factory spacer the rears are tucked in too far, a 30 or 35mm spacer would work much better IMHO.

Cheers

Hilton

Thats a huge difference in unspring weight per corner! Interesting - I have a mix of Mille Miglia and original GTS Cup II's on one of my cars (the fronts are Porsche, rears are MM), I'll have to start keeping an eye out for proper rears as I didn't realise the difference was so great in weight.

The ET difference is enough to take you from positive to very-slightly-negative scrub radius, which is why stability has improved massively - the steering will be fairly neutral and require a lot less input from you to hold a straight line. You'll find higher offsets feel even more rock-solid than the ET55.

rexpontius

Today I replaced the hand-brake pads and fitted a pair of 30mm spacers (original Porsche 993 parts) at the rear axle instead of the factory 21mm spacers.

This pushes out the rear wheels just that bit more, so it really looks great.

Took the car for a drive this afternoon, and the handling is just amazing. The higher offset front wheels make all the difference, it does not tramline anymore and is very stable up to very high speeds (did about 230 kph ;-))

I still have the 205x50x17 Michelins at the front, and I have to admit they work fantastically.
I do not feel the need to swap them for 225x45x17s, and an additional benefit of these narrower tires, is the lighter steering!

To lighten the steering I already modified the PS pump line, but with the 235 tires up front it still felt really heavy. With the 205's steering is very pleasantly light and makes the car much more fun to drive.

Will post some pictures tomorrow. Now it is time for a beer :-)

rexpontius

Got myself a set of nice new Pirelli P-Zero rosso tires and got them mounted on the new rims this morning.

Pictures below :-)

Randy V

Looks good.

Would look even better if you fitted them with painted center caps.

rexpontius

I considered the painted centre caps but I am not so sure if I like it better than these silver caps.

I also saw some silver caps with "real" looking silver logos on them.

What caps did porsche use on factory fitted Cup IIs ?

Vilhuer

There were at least two or three different caps available from factory plus painted to match version for painted wheels. Most common was probably silver with some black in Porsche crest.