Speedo gear help please!!!!

[brans87]

I am wanting to replace the gear for my speedo to read correct mileage since tire and gear swap. Can anyone assist me in getting the correct one ordered?

87 K5
700R4
4.56 gears
new goodyear duratracs 35x12.5x17 outside diameter 34.8 being new
np208
Anything else needed to find right one?

 

[Kain]

is it to fast or to slow, the speedo. what color is the one you have

 

[blazinzuk]

Yep we need percentages man! Percentages!

Also I'd measure your static loaded radius of the tire. Cause it's gonna be different than advertised tire diameter. Static loaded radius is the tire on the rig. Proper air pressure in it. Measure from the ground to the center of the hub.

It can be calculated but I don't remember how right now.

If your speedo works get a GPS speedo for your phone. Check it at several different indicated speeds. At 35,45,55, and 65. Calculate percentage difference from there.

 

[paratrooper307]

Going to numerically higher gears and larger tires is typically going to make your speedo read higher than your actual speed. Input your data into a calculator like this one. Use a GPS app to confirm. Then find a speedometer gear or reduction box to bring you down to where you need to be. Depending on what gear combination you started with, it may be pretty close to right (if 3.73) or it could be a ways off (if 3.08).

http://www.4ws.com/speedometer-calculator-new-tires