2nd Gen Non-Engine/Transmission loaded tire radius or circumference??????

[bkroupa]

I just ordered some 285/75's & 8" wide wheels for my truck & was thinking about the speedometer error. I've read where people thought you had to figure the rolling distance by the loaded tire radius, but the circumference of the tire is constant. So a tire with a 103" circumference will roll 103" per revolution no matter what the loaded radius is... . Right???

 

[Tcolesanti]

I would just find a radar trailer! :-laf

 

[bkroupa]

I have a GPS I'll use to check. It's just never made sense to me that the loaded tire radius effects the effective gear ratio of the tire. Look at a tank track, it ain't round.

 

[DPelletier]

So a tire with a 103" circumference will roll 103" per revolution no matter what the loaded radius is... . Right???

Right.





Dave

 

[DirtyDodge]

calculate tire size difference



((2 x 265/25. 4)(75/100)+16 = 31. 65" tall tires

((2 x 285/25. 4)(75/100)+16 = 32. 8" tall tires



31. 65/32. 8 = . 965% difference.