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Wheel Swap

Posts: 87
Joined: 05/08
Posted: 03/25/13 11:11 AM

My 2006 Mustang GT came from the factory with 18" wheels. If I changeover to 17" wheels would I have to have my speedo recalibrated or change tranny gears  

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Posts: 96
Joined: 04/12
Posted: 03/25/13 06:02 PM

speedometer calibration depends on the ROLL out of the tires...

how many times per mile they turn... not rim diameter..

go to tire rack... look up your 18" tires... if you click the specs tab.. you will see the how many turns per mile...

then look up your new tire specs... how many turns per mile..

i don't know off the top of my head what year ford went to electronic speedometers.. probably somewhere in 1985 or 1987...

how to calibrate the speedo????? that i have not looked into..

does your cell phone have a GPS... how far is it off..   probably won't make much of a difference..

only people who would care...  would be leasing companies or car owners who don't want to pay too much to their lease..

just think... lease a car... take the 3:08 gears out...  put in some 4:11 gears...  

you are going to get to 80,000 miles... 20, 000 miles early..  at that would throw off the speedo 25% or so.  

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