It is very easy to change the gears. There are a wide range to chose from. Was it right before you changed tires. If so figure out the differents in tire higth. What percent taller did you go? If you know the percent, count the teeth on the gear and multiply by the tire percent.

I just changed gears in my Dodge. I went from 3.21 to 3.50, this is pretty close to a 10% increase. My speedometer gear was a 29 tooth, so to speed up the reading I had to go up to a 32 tooth. 29 to 32 is almost 10%, its now reads right again. This works just the same using tire higth.

Just go down to the local transmission shop, they should have the gears. The housing inwhich the gears fit is adjustable. You will have to turn it so the gears mesh. It should be numbered in groups or ranges of gear teeth. Joe