Drop it down to 34.5, keep in mind resolution error of the reprogram and Waze/other tools will always show some degree of offset.Speedometer calibration issues
I have Nitto Ridge Grappler 35 x 12.5 x 17 tires on my jeep rubicon JL and used the Flashcal to change the tiresize to 34.75. The speedometer is consistently off by 5%, Jeep shows driving at 42 miles/hr vs. waze or other speedometer tools at 40 miles/hr. Has anyone else faced this problem and found a fix? I will do hit and trial by lowering the tire size, which might help but it's not the right solution.