How to recalibrate your speedometer after changing tire sizes or gears

[machoheadgames]

Reading faster on the GPS than the speedo after I replaced the part.

So going 65 on the dash, 70 on the GPS?

If that’s the case, you need a 29 tooth gear.

65 * 31 / 70 = 28.8

I never recommend anybody buy their gear based on a chart or nominal tire size. Math is always the best way to get it accurate. Too many incorrect charts out there and too many fluctuations in real world tire diameters.

 

[Viking Jeeper]

Or, just buy the electronic solution and be done with it.............https://www.12oclocklabs.com

 

[AWTJ2000]

So going 65 on the dash, 70 on the GPS?

If that’s the case, you need a 29 tooth gear.

65 * 31 / 70 = 28.8

I never recommend anybody buy their gear based on a chart or nominal tire size. Math is always the best way to get it accurate. Too many incorrect charts out there and too many fluctuations in real world tire diameters.

Thanks so much for the response!

We actually had it flipped- 65 on speedometer, and 62 on the GPS.

 

[AWTJ2000]

So going 65 on the dash, 70 on the GPS?

If that’s the case, you need a 29 tooth gear.

65 * 3 / 70 = 28.8

I never recommend anybody buy their gear based on a chart or nominal tire size. Math is always the best way to get it accurate. Too many incorrect charts out there and too many fluctuations in real world tire diameters.