Mine only caused a problem with the timing lights when using Kevin's skinnys on the front. With the 245-45-17s I've got about 3" of ground clearance between the air dam and pavement, with the skinnys I only had about 2 inches. If my car wasn't lowered it wouldn't be a problem.
David
PS: I recall Mike Puckett having to trim his down about an inch several years ago because of the same thing.