akolodesh

993 c2 : I switched from my stock 17" wheels (255 tires in rear) to 3 piece 18" 10 inch wide wheels (2 inch lip) with 285/30's in the rear. I have the Bilstein hd's with M030 row springs (wheels/ alignment/ corner balance all done by Forgeline - these guys do MANY race cars and are very experienced). When I hit certain dips my tires rub on the fenders, otherwise driving is fine - even on speed bumps. Forgeline has shaved off a portion of the wheel and rolled the fenders - this has helped but has not solved the problem. Clearance while the car is at rest seems fine. Other than taking a 1/2 inch off the lip of the wheel. I don't know what to do to fix the problem (this is not a solution I want to go with).
Any others ever had this problem? The guys over here are running out of potential fixes. I thought possibly changing to a stiffer spring might help (I also have the TT sway bar in - 23mm with an extra hole - set to stiffer setting).

David in LA

I don't think stiffening the rear sway bar will help much...I think you have to do one or some of the following: 1) install new springs and/or shocks; 2) use 265s in the rear (this will also reduce your understeer); 3) get new rims; 4) swap to tires with a more rounded profile (what tires are you using now?); or 5) increase your negative camber setting.

Assuming the camber is already at -2 degrees, if it were my car, I would ideally get new rims with the proper offset and if this isnt possible then I would swap to 265 tires with a more rounded profile. What rims are these and what is the offset? It seems your rims do not have the right offset...fyi my 98 C2 has 285s on a 11" rim with rolled fenders and no rubbing.

TheOtherEric

Ditto David's comments.

Proper offset is 65mm. I'm guessing you're in the ballpark of 55-60mm.

Rick Lee

Hmmm. I just got the 996 Carrera 5 spoke 18"ers on my lowered 993 C2 non-widebody. This has me worried. I haven't noticed any rubbing and I'm running 285's in the rear.

FlyYellow

i had the same probelm - i added another -5 degree of camber for a total of -2.5 degrees and it solved it... i would also check the oil line on the inside and see if it is rubbing. believe it or not but -2.5 degrees solved it.

cheers,
boris

kary993

I think my 10 inch BBS race wheels have an offset of 45 but the outer lips are 2 inches (I also have some 10.5 rears same outer). Fenders are rolled and camber is just shy of 4 degrees. Very close fit with a PZero slick 285/645/18. That said you must have an offset of around 55 possibly. Camber will fix the problem if you are rubbing anywhere on the upper fender area. Although your tire wear will severely suffer with camber of 2 degrees or higher, if your suspension can even get that much camber into it. Try a 275 or 265 size tire if you do not want more camber. That should work.


Check that first statement, the rears are a 50 offset!

TheOtherEric

Rick- your 5-spokers have the proper offsets, so I wouldn't be too worried about rubbing in the rear. I've read numerous times here that 285 is ok with proper offset wheels. I have 285s in the rear of my lowered car, too. Haven't been on the track yet, but so far so good. And I'm really low (24.75" or so)

Viken

2" lip? Sounds like too much negative offset. Do you know what it is?

akolodesh

I DO NOT KNOW WHAT THE OFFSET IS BUT WILL FIND OUT TOMORROW. THANKS FOR ALL THE GOOD ADVICE.

dale_loch

Alex,
You made mention that you have a 993 C2. Your profile is listed as 993 Targa? There is a difference. I can't remember where I had read it, but there was an article that referenced the specific wheels for the Targa. The Targa wheels were specific from Porsche for Targas. It had something to do with the reduction of body roll and squeeking (glass roof). You may be having problems due to going to the larger size (The body fenders may be different on Targas). I am not 100% sure on this (I do know the Targa is built on the Cab frame, narrow body) but if you do have a Targa, try asking other Targa owners if they had any issues (I haven't upgraded my wheels yet).

Just my 2 cents.

David in LA

The problem is with his wheels as the rear fenders are identical.

OT - how long have you had your TPC kit? Any major issues? Seems like a number of people have done this recently and I'm getting tempted. TIA

Monique

18's Speedline on our car. But we use 265's only coz with the lowering and M030.. you end up with some rub. Though my camber is very aggressive (car is set for track) I wouldn't go for larger tires.

One step back for mankind

akolodesh

Hi Dale,
I got rid of the targa and got the c2 recently. Need to post before and after pics. The rubbing only occurs on the lip of the fender and only when I go over significant dips. The problem that I keep coming across is that Forgeline is a well known and respected racing wheel maker (I am lucky to have their corporate office and manufacturing facility only two miles from my house). They have tried practically everything and according to to them the wheel (18", 10" wide, 2" lip) w/ 285/30 michilen Pilot Sports should fit fine on this car. Especially since they also did the alignment and corner balance. These guys know their stuff. That's why I am so puzzled. I have a call into them to find out what they used as for their offset and camber. Will post accordingly. Thanks all!

DJF1

I suspect the Offsets as well... I have 285's Pilot Sport Cups in the rear, NO rolled fenders and negative camber of about -2.5. These are mounted on Kinesis Supercup wheels.

David in LA

Probably a longshot but you may want to measure the wheels and the offset. Most likely not the case, but errors in assembly happen with everything....good luck.