FrankNBrew
NAXJA Forum User
- Location
- Royal Oak, MI
I have an issue with the speedo gear charts I see published on various sites. Here's what I have:
I went from 245/75/16 MTRs to 285/75/16 MTRs. 245s run 684 revs per mile. 285s run 635 revs per mile. I had a 32 tooth speedo gear, which was accurate to within 1.5%.
Now, according to the speedo gear charts I should be running a 31 tooth speedo gear with the 285s. I figure it should be between a 29 and 30 tooth speedo gear. Here's why:
635/684=0.928
32*0.928=29.696
This being the case, I should use a 30 tooth speedo gear to be within 2%. As the tires wear, the speedo should become more accurate. With a 31 tooth gear as the charts suggest I will be 4% off from the start, and the speedo will fall further out of accuracy as the tires wear.
Am I missing something here? Am I using fuzzy math? Help me out!
I went from 245/75/16 MTRs to 285/75/16 MTRs. 245s run 684 revs per mile. 285s run 635 revs per mile. I had a 32 tooth speedo gear, which was accurate to within 1.5%.
Now, according to the speedo gear charts I should be running a 31 tooth speedo gear with the 285s. I figure it should be between a 29 and 30 tooth speedo gear. Here's why:
635/684=0.928
32*0.928=29.696
This being the case, I should use a 30 tooth speedo gear to be within 2%. As the tires wear, the speedo should become more accurate. With a 31 tooth gear as the charts suggest I will be 4% off from the start, and the speedo will fall further out of accuracy as the tires wear.
Am I missing something here? Am I using fuzzy math? Help me out!