I tried a set of MT drag radial slicks size 14.5 x 33 x15 back in 2004 . i ran into a problem others tagged as "radial rock". The car would twist back and forth like a gorrilla was pushing sideways on the front and back of the car. I wound up having to lift on half of the passes because it was so bad i thought i would lose control. The car would not settle down till i lifted. People asked me why i didn't lift on a couple of runs, one of which was the fastest the car ever went. Nobody has ever come up with why this happens, or at least haven't shared the info.