2015 GMC Sierra 5.3 6" lift 35" tires

[Betro]

When I change the tire size on the InTune to 35" the speedometer is still off. Checked with two different GPS's, GPS by phone and GPS by my radar detector. I found that setting tire size to 33.5" actually sets the speedometer closer to accurate readings. Anybody else have this issue?

[mikel]

not uncommon at all, thats because your 35" tires are actually 33.5" tall

[Betro]

not uncommon at all, thats because your 35" tires are actually 33.5" tall

Actually they're 34.7" tall