[Hunter5179]

245/35/20 fronts Speedometer Difference: 0.154% too slow with a diameter difference of .15%..............For 275/30/20 rear's Speedometer Difference: 0.834% too fast with a Diameter difference of .83%........For 285/30/20 rears the Speedometer Difference: 0.077% too slow with a Diameter Difference of .08%

The difference in rolling diameter for either of these compared to stock is really negligible and should not affect the x drive at all.. Its when rolling diameters exceed 2.0% and definitely above 5% is not good.