I had a set of 26x10.5's on a 8.5" rim and I was in the low 1.7's. I switched to the 26x11.5's and I averaged in the mid-high 1.6's with a best of 1.64. This was with good track prep. The 10.5's did sway a lot. I had to keep the pressure up around 13-14psi to limit the sway. The 11.5's...