Speedometer showing double on 89 mustang

Aug 02, 2009 1 Replies

Hey everyone,



trying to figure out what would make my speedometer show almost double after going from a 15" rim to a 16" rim with 245/45 tires? I do not remeber the tire size on the 15" rims. From what I have found on the Internet it should have only changed my speed by about 2-3 mph. With the 15" rims it was showing about 16 mph high. I do not know if it still has the factory gears. I have a 16 tooth gear from another transmission that I have but not sure if it would help. Any ideas before I start replacing speedometer gears? It is a 89 lx 5.0 convt with a T5 transmission in case it matters.



Thanks for any ideas. I have searched the internet and did not really find anything about a speedometer showing double.



Your ratio for rear gears is the number of rotations it takes the drive shaft to spin the wheel once around.

After you get that, (jack it up and spin your wheel once around) go here,

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find the seven tooth gear for yours.

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