2 questions on wheels/tires

NZ94Stang5.0 · 06-07-2007, 04:20 AM

Fist of all, is it true that upping wheen size from 16 to 17 inch for example, will throw off your speedometer?? If so, how can that be fixed?

Also, i have a 94 gt with Slp loudmouths, they are lower than most exhausts bc of the with and i was wondering what is the biggest tires i can use with 17" cobra r rims. I was told 315s will deffinitely rub the tailpipes.

thanks, Nick

Norm Peterson · 06-07-2007, 11:25 AM

(1) Not necessarily. As long as the OD of the two tires in question remains the same (the revs per mile numbers in the 'specs' pages for the two sizes on the Tire Rack site are within a few rpm) you wouldn't have to do anything.

But if this is not the case, you'll need a different speedometer driven or drive gear. Swapping the driven gear is pretty simple, butif you have to replace the drive gear because the driven gear you need with your existing drive gear is not available means you have to open up the tranny. Inline correction gearboxes that you'd have to splice into the speedometer cable at least used to be available (and may still be if you can find a place that supplies the time-speed-distance road rallye market - starting a search with 'SCCA' may be of some help). If you happen to have an electronic speedometer it may be possible to get it re-calibrated. Some aftermarket electronic speedometers you can recalibrate yourself.

(2) No idea.

Norm

NZ94Stang5.0 · 06-08-2007, 02:06 AM

thankss alot!! does anyone know or have experience with the 2nd question though??

kaichele1 · 06-08-2007, 02:57 AM

yes the 315's rub...