Proper height for 275/70/18 tires with Hypertech?

[1057]

Brand new 275/70/18 Cooper ATP's installed and fit perfectly. Unless my math is off they are 33.20". Closest setting on my Hypertech Max energy is 33.25".

 

Well speedo is reading 3mph fast. IE for clarification, speedometer is reading 60mph and I'm actually traveling 57.

 

Is my math messed up?

[8.1HD/ALLISON]

Nope, I show 33.2 inches also, but tires can vary a little. Try changing to 33.0 and see how it reads?

[1057]

Nope, I show 33.2 inches also, but tires can vary a little. Try changing to 33.0 and see how it reads?

I'll give it a try. Thank you!!!!

[Big Whiskey]

Do you have a tape measure? Measure the actual height of the tire as it sits on the truck. That's really all that matters to your wheel speed sensors.

[1057]

Cool, I'll try that first on Friday on my first day off. I really appreciate the replies guys!