Thanks guys I am leaning toward buying 38x12.50 tsl's for this upcoming season.  I was playing with the idea of 39.5 iroks but I still like to drive it on the street occasionally.  The 38's will be significantly smaller and narrower than the 39.5's though.  My 36sx's measure about 31" to 32" aired down to 6 psi, looking for a little more height.