First of all I searched but my search terms are too short, TGO requires at least 3 letters to search.

I want to know if I can fit 255/50-16 front tires on a 1991 RS with the Aero ground f/x without hitting the f/x with the rear of the front tires.

 

with the stock IROC-Z rim you should be fine. before i got my 18in IROC wheels i had the stock IROC wheel and i ran 245/55R16 and had plenty of room.

 

Yes they will fit, lots of people run 255/50-16's so 15's will be fine.

 

Yes, I should have mentioned I am running stock 1986 Z28 wheels (16") with 255/50-16's.

If many people are running this combo why am i having a problem? The rear of my tires are hitting the valance f/x on both sides when turning but more on the passenger side. I have not drove it as it is for fear of damaging the f/x.

The actual car isn't a '91 RS but a '86 SC with the '91 RS f/x recently installed.

Cam I adjust the caster to move the front wheels more forward slightly? I do believe 1/2" should do it.

 

Who's running 15's?

 

Are there different offsets with different year IROC wheels?

 

Oops sorry, i am a moron, it said 16 and i read 15. I've been 1 behind all day. You could adjust the caster, what is it now? The tires should not be hitting if you have the camber and caster set for performance. Adjust your caster in the postive direction, top of the strut back and your camber negative, top towards motor. Normally maxxing out the caster and camber works pretty good, it should also help out your rubbing issues too.

 

The top of the strut is already all the way rearward on the passenger side, almost all the way rearward on the drivers side. The dirvers side doesn't hit as bad as the passenger side.

Shouldn't the top of the strut need to move forward to move the wheel centerline forward? How much movement of the tire can I get by moving the top of the strut?

 

No you are increasing the angle of the strut and wheel. But really the tire shouldn't move much at all. You might have something tweaked or your springs are sagging or something on that side.

 

Nope, nothing tweaked or bent. The car drove straight. I totally re-built the steering with the PST kit plus extra missing parts and replaced all rubber bushings with poly. The spings are brand new Moogs also, look at my fender height they havn't even really settled down yet.

I figured that the tire size alone is the reason why they hit the f/x. That's why I asked if any members '91-92 RS cars with 255/50-16's installed have a problem or not. Close up pictures would be appricated.

 

I run 245's on the front on my 91RS, with the earlier IROC wheels though (single groove down each spoke). They run really close to the GFX. About 1mm off! 255's may rub on mine.

Andy.