jscott82

is there anything you dont know?

Bill Verburg

When to shut up

V

When you say "rub" I assume we are talking about the tire and not the rim. With that in mind, you could increase the rim width from 8" to 9" (or possibly even 9,5") without changing the offset and using the same tyre. The tire will then be stretched on the rim and therefore not reduce clearance by as much as the difference in rim width (if that makes sense). The difference in rim width is 0.5" both to the inside and outside (8x18 ET52 vs 9x18 ET52) but the difference in clearance might only be 0.25" because of how the same size tire sits more stretched on the wider rim. Lot's of factors to consider here. 235/40/18 is a pretty high tire whereas a 245/35/18 tire can help if tire height is an issue so eventough it's wider it might make for a better fit. Trial and error is really the only way to go. Every car is unique, as david said.

To illustrate how much a stretched tire can help increase clearance, here is an example. On my previous C2S I had a 285 Michelin PS2 (very wide tires for their size) mounted on a 10x18 ET28 (effective offset with spacers). There was slight rubbing on the fender lip because the tire "bulged" out much further than the actual rim they were sitting on. I was able to run the same tires on 11,5x18 ET33 rear wheels with no rubbing. So clearance was a little bit better. Same tires. And - here's the point, the 11,5x18 ET33 rims extends outward by 14mm(!!) compared to the other wheels. Needless to say, the rims also extend to the inside and the tire was very stretched on the 11,5" rim. But just to give an example..

On my 993TT I run RH 3.6 speedlines 9x18 ET40 with Contis 225/40/18. No issues but would probably rub if I went down any lower.

Is it the consensus that 9x18 ET52 is about as far inboard as you can go (0.5 inch more back spacing than the stock 8x18 ET52) in the front of a 993 without issues?

V

Yes the 996cup wheels! Very nice. High quality and very light. For those of you interested, the front has 8" inner hoop and 1" outer hoop. Rears have 9,5" inner hoop and 1.5" outer hoop. The centers are identical.

jscott82

One thing to point out to anyone considering the E88's. They have VERY thick centers (or at least the set I had my hands on)... Stock wheel studs are too short, you will need to replace them with much longer ones to work with these wheels.

Macca

Hi Bill.

Please could you give me the benefit of your advice.

I am about to commission some wheels to be built for me by Kerscher in Germany. They are 3 piece speedline style. 18". Mr Kerscher has recommended the following fitments for my 1995 C2. What are your thoughts? Will these work? I havent yet made a tyre choice but suspect I may consider Pierelli Corsa Dot rated:

8Jx18 offset 48mm
rear 10,5Jx18 offset 54mm


Cheers

Macca

Hi Bill. I should add. My car is sitting at approx 1/4 inch above RS spec height.

Cheers

Matt Lane

Really? That's the first I hear of that. Can anyone verify?

Matt

Mark in Baltimore

I thought rolling fenders is a prepared change. I have a hard time believing that stretching a fender is allowed for a 993 running in class as a G car. If you have an email from Donna supporting stretching and rolling, I would love to have it for my files.

jscott82

You scared me for a sec... I had to go look this back up.... Its under the tires/wheels section.

One inch wider than originally supplied wheel and any tire combination which fits inside the stock body without rubbing and without modification exceeding “rolling” or “grinding” of the outer fender lip is allowed.

Mark in Baltimore

Cool. I was under the impression that rolled fenders was not allowed for a stock car. Someday, I'll learn to read.

Bill Verburg

I don't like those o/s
here is the layout of a 993 front wheel well, the top wheel is an 8ET52(oem fitment) the second wheel is a 9ET52 the 3rd is an 8ET52 both of those work w/ 225/40 tires at all heigths, the blast will has also been reported to fit though I'd be a lot more comfortable w/ 8.5ET56 which I know works w/ 245/35 tires on very very low cars.



In back is where the real issue is, the bottom 2 I have used on my car 10ET65 and 10 ET52. The bottom wheel is a 10 ET52 which works w/ 265/35 at RoW M030 height but kisses rolled fenders at RS and lower. It sticks out 83.4mm compared to 10ET65 that sticks out 70.4mm which works at all heights. the others have been reported to work but at higher heights. I wouldn't use them if they stick out more than the 10ET65 70.4mm.

tjangi

Bill, good job tks for that. Even I understand it better now...

jscott82

The ones I tried may have been Magnesium centers,not sure if that makes a diff or not, they were also off a 996 cup, not sure if that is different than the off the shelf ones. But I had them in my grubby little hands and on the car, I already have longer (66mm) studs installed and even they were too short. I would contact BBS and ask them directly....

Macca

Bill,

You have been super helpful and those diagrams are majic.

Lets assume Im running my car RS spec height with 235 18 front and 285 18 rear with an acceptable amount of camber for a fast road and occassional track car.

Assume fenders not rolled. Assume a dot rated tyre like Corsa or Pilot Cup.

If I want to have custom designed 8.5 front and 10.5 rear width rims and I can have any offset I wish but whant to maximise the asthetic appearance of the vehicle do you think the following will work in your opinion?

8.5 52
10.5 58

Or given im importing these from Germany and cant easily return them would I be better to go on the safe size and say:

8.5 56
10.5 58 or 60

I dont know what te exact flange thickness is but lets assume its not going to be far from what your diagrams indicate.

I have a pair of 5mm OEM factory spacers so Im wondering what the safest option is for me. I guess with the spacers I could always adjust the ET if need be for asthetic reasons assuming no rubbing (which I would like to achieve without rolling fenders if at all possible).

I value your input and experience on this so would be keen to hear your views and thanks you in advance....

Thanks