What could possibly be wrong. My 300ex is hitting what sounds like the rev limiter half way through the max rpm's in 2nd and 3rd. I've always run 18in tires and run 14/36 and it has never done this before. I know for sure the engine is not revving high enough to be the rev limiter. The new tires i'm running are 18-11-10 fast trekkers. U think them being smaller then most 18's could be the problem.