msobota

I have created a Webshots photo album to detail this now confusing and very expensive problem.

My rear tires rub over the slightest bump in the road - any bridge crossing etc...The rear wheels seem incorrect for the car (too wide - too outset). They look great but they are so far outset that the tires do not tuck up into the fender well but instead hit the fender well lip at about the 10 oclock position the worst. I have rolled the fenders as much as I can without doing damage to the fender.

The Webshots address is : there are 6 photos

http://community.webshots.com/script...98967524nYPYgh

Here is a detailed description of what is going on.

My car is a 1996 993tt - I want the car to be very stiff and very low to the ground.

The wheels are HRE 545R 11x18 rear and 8.5x11 front
Tires - Michelin Pilot Sport 315-30-18 Rear and 235-40-18 front

The suspension is H&R Porshe Super Cup Racing Suspension - The suspension is set to its highest possible setting and the height is approx 24.75" at the rear wheel well top - 25.5" at the front wheel well top. Obviously, this suspension is designed for people who want their car very low.

I do not want the car to be higher and as a matter of fact the left side of the car is going to need to be lowered a bit because the suspension is set at it's maximum height all the way around and the left side of the car is 1/8" higher than the left at the frame.
To make the sides even the only choice is lower and this will probably result in the left rear wheel rubbing as badly as the right side is.

I like the look of the wheels and tires but after analyzing this and scratching my head a good bit, I have come to the conclusion that the wheels are tires are incorrect for the car. It seems to me that if the rear wheels were 10.5" instead of 11" or just not outset quite so far that I could lower the car an additional 1/2". There is at least 1" of room between the wheel spokes and the calipers and there is at least 1.5" on the inside of the wheel where the half axle connects.

One of the measurements I took was from the wheel rim to the outer most part of the top of my fender well - this is 1/2". (see photo) I think this is the problem. It would be helpful for me if some of you with wide wheels and tires and low cars could give me the top of rear wheel well to ground measurement (mine is 24.75 and also the wheel to outside of top of fender well measurement - Mine is 1/2". I think it needs to be more like 3/4" at this point for the wheel to properly tuck into the fender well and make the car a little lower.

The shop says that HRE can shave 3mm off the hub and they can run 3 deg negative camber that might allow the wheel to tuck inside the fender well. I doubt it and I am not sure about running 3 deg negative camber - Thoughts on this would be helpful.

Another option they might recommend is a different suspension that would raise the car but I don't think that the car is too low. I really don't think it's low enough.

It is amazing to me that I am left to figure this out on my own after spending $18,000 on wheels, tires and suspension.

What do you guys think?

Thanks very much.

Mike Sobota

highest possible setting

msobota

Corrections: I spent $14,000 on wheels, tires and suspension.

The right side of the car is 1/8" lower than the left at the frame - I will need to lower the left side to compensate.

I have intentionally left the name of the shop out of this at this point. I am hoping this will encourage them to make their customer happy.

Mike Sobota

ca993twin

Mike,

My 1996 TT is (poorly) equipped with ROW springs and stock (worn-out) original shocks. My car has Kinesis K28 wheels, 18x10.5 rear and 18x8.5 front. I took the same measurments that you did and my results are: the height of the rear fender lip is 25.5", and the tire is inset from the outermost fender edge by 7/8". I use Yokohama AVS Sports in 295x30x18 size.

Your car looks great, BTW. I think you can solve this problem by changing out the rear tires to either a different BRAND (different manufacturers will have substantially different sized tires, even in the same "size" spec), or changing to a 295x30x18 tire. To use most 315x30x18 tires, the offset of the wheel must be very carefully computed to get the tire exactly centered in the wheel well.

If you don't mind a pleasant road trip to So. California, we can try my wheels on your car, and see how they work.

SPR

You are running too wide of a tire in the rear. that is your issue of rubbing. Go back down to 295's on a 11" rim and you should have no issues. Also check what your offsets are and compare them to the offsets of the 01 and up turbo rims which also have 11" rear as they have no issues with clearane or rubbing.

Glen

I run 265 fronts on 9's and 315's on 11's rear and have No rubbing and no fenderrolling at all. I have 2 different sets of wheels I do this with. BBS 3 piece that I am selling with brand new MPSC's and Forgelines that are staying with the car. As I said they both run that width no proble, no rolling and no rubbing. Please PM me if You need specific backspacing etc... You can bolt up a stock 996 TT rear wheel and it will hold a 315 and not rub at all either. It has a 45mm offset in the 11 inch width. Your stock 10's for your 993 TT featuire a 40 mm offset so You can see clearly that in your application You have a ton of inboard room before contact with your spring coil or your oil S pipe. Probably on the order of 1.5 inches if You rach back there.

SPR

wel sounds like either the offset is wrong or the alignement between the two setups is different camber wise, and or different rear tires also stick out differently even at the same size with the fatter sidewalls.

viperbob

Whoever sold you those HRE wheels gave you the wrong offset. I use 996TT wheels for the street (18x11s) with 315s and have no issue running a fender height of 24 3/4" in the rear with a 2.5 degree negative camber. On the track, I use a similar wheel with 315 Hoosiers, but even use a 6mm spacer to push the wheel out towards the fender. And guess what? No rubbing. I would not shave a wheel. For the money you spent, I would make the place give you the correct wheel for your car.

msobota

Thanks Bob - That is the post I was looking for. I remember that we discussed this earlier and that there was somebody out there with the answer.

I sent an email today asking the dealer to order the correct wheels for my car. Then I will be able to get the H&R Racing Susp off it's max height setting and my stomach will stop tensing up each time I go over a bridge or uneven road surface.

Mike Sobota

msobota

Glen - Thanks for the specifics - What should I tell HRE I am looking for? A 996TT wheel? That seems so odd that they wouldn't know what properly fits a 993tt.

Thanks.

Mike Sobota

viperbob

What I am sure they tried to do was take the factory 993TT 10" wheel, and give you an offset the would work with and 11" wheel. Too bad for them Porsche already has the proper specs...

Here is the offset that will work on the rears:

996TT wheel sizes (hollow or solid spoke)
Rear - 18 by 11 ET 45

This offset has worked with some 315 Hoosiers, Michelin Pilot Sports, and Michelin Pilot Cups on the rear of my car.

Good Luck...

Glen

It looks like You can run a 55mm to a 58mm offset on the front in a 9 and a 45 to 52 mm offset on the rear in an 11.

msobota

I spoke with the folks at HRE and they are ready to take my wheels back to make things right. They claim that the offset on my 11x18 wheels is 34 mm and that this offset would work properly with 295-30-18 tires but not the 315-30-18 my dealer promised I could use.

I told them I need a 45 mm offset. Is that the stock 996tt offset? Viper Bob - Are you running a 45mm offset with a 6 mm spacer?

Mike Sobota