What PSI size you running?I'm running BFG all terrain 37's and set mine at 35.86. Easiest way to do it is to download an app such as Waze which tracks your speed and match it up to your speedo when going down the highway. First setting was 35.75" and I went from "stock" 6 mph off to just 1 mph off. Then I bumped up to 35.86 and matched the gps spot on... Easy Peasy