Skip to main content
Topic: what size rear tires to correct speedometer... (Read 920 times) previous topic - next topic

what size rear tires to correct speedometer...

I have 17" Rims, 3.55 gears, and a 22 tooth speedily gear. Anyone know the equation to get the speedo as close to accurate as possible using tire sizes?  Wanna get it close enough so the cruise control will work properly.
:cougarsmily:5.0 HO, E303 cam, Exploder/Cobra intake, smog pump delete, Ford Taurus electric fan, MAF conversion, BBK headers, MAC 2.5" off-road exhaust w/x-pipe, AOD w/shift kit, 8.8 Trac-Loc rear w/disc brakes, 5-lug conversion w/'98 Mustang GT 17" wheels, Mach 1 springs:cougarsmily:

what size rear tires to correct speedometer...

Reply #1
well then you just need to keep the same size overall OD of the stock tire

so if you had a 225/60/15 the od would be..25.6 inches
so for a 17 you would have to run a 245/45/17 and that is a OD of 25.7

you can play around with tire sizes and gears here..http://www.accuautoparts.com/calculatorfin.jsp

 the crusie is vac operated, so the tire size will not matter, but it will mess with your speedo
1985 TC (yet another one) Fully loaded
has 225k mile  still with the factory head gasket






84  Turbo ranger  Daily driver  ($800.00 Ebay deal)
          volvo FMIC and more getto rigging than the law should allow

 

what size rear tires to correct speedometer...

Reply #2
Speedo driven (the one on the end of the speedo cable to transmission adapter) and drive (the one on the output shaft of the transmission) gear calculator:

http://www.sccoa.com/faq/speedgr.html

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp