C3 1979 interference between wheel and fender

[Yves Thaens]

Hi

I just mounted the original aluminum wheels on my car with 255/60 tires. Right front side : the tire hits the fender in the rear (bottom). Is this common ? Car has not been hit, nor had any accident. What can be done about this ?

[Joe L.]

Re: C3 1979 interference between wheel and fender

Yves-----

If the car was not originally fitted with 255-60-15 tires (they were optional for 1978; 225-70-15 were standard), then the area that you describe was not "factory prepared" for clearance with such tires.

[Yves Thaens]

Re: C3 1979 interference between wheel and fender

Joe,

If I'm correct the sidewall on a 225/70 would even be bigger ... I don't think this is the problem. BTW : left side fits perfect, clearance is about 1/2".

Also, left side has problems when turning the wheels the other direction. In this position it is real close to the front of the fender.

Yves

[Tom R.]

Re: C3 1979 The Fix...

Yves

To prepare for the larger P metric series tires, the factory removed fender material for clearance.

The inside lip at the top of the front fender on each side was removed along with lower rear edge of the front fender. From time to time, we'll do a check on the judging field of 78-79s. You can feel the lip almost blend in with the fender at the top and than return to a normal lip for models prepped for the 60 series.

Before grinding...you may wish to check out a Pace Car or other 60 series equipped model just to get a feel for how much material to remove.

[Joe L.]

Re: C3 1979 interference between wheel and fender

Yves-----

The OVERALL DIAMETER on a P225-70-15 is slightly larger than a P255-60-15. However, the P255-60-15 has a much greater SECTIONAL WIDTH and much greater TREAD WIDTH. These two parameters are what causes the interference.

There are often side-to-side chassis differences on a Corvette caused by manufacturing tolerances and/or wear over the years. That's probably why one side seems to fit ok and the other not. The original amount of factory "clearancing" was not great. In some cases, the P255-60-15 tires might have "fit" without clearancing. However, the clearance would have been minimal and "touch-and-go". So, the clearancing was done to ensure that sufficient clearance was present in all cases.

[Yves Thaens]

Re: C3 1979 interference between wheel and fender

Thanks,

Just how much clearance would it need both in the front and back of the wheel well. I don't not have a 78 pace car at hand to feel what clearance it has.

I took off some of the material at the back, just enough so there is no fiberglas visible anymore behind the moulding. It seems to just get passed it now, with some 1/5". If this is not enough I would have to saw of a piece of the moulding in that spot.
In the front the problem is bigger. The pace car spoiler seems to be touched by the tire just a little bit before the suspension hits the stop. Grinding of the spoiler at that place ? There would still be little room ...

Yves