Speedo calibration

***ju015dd*** · #1 (**permalink**) 12-14-2009, 12:01 PM

I know they are only 33 in tires but any idea of how much they through off the speedo. Also would the speedo being off also make my odometer wrong too? Just curious about this for oil changes. Didn't know how far off it....

no-tel-in · #2 (**permalink**) 12-14-2009, 12:02 PM

when I ran 33's it was only like .5-1 mph off... and yes it does affect your odo.

***ju015dd*** · #3 (**permalink**) 12-14-2009, 02:02 PM

It would show more on your odometer than you really have correct?

layson · #4 (**permalink**) 12-14-2009, 02:17 PM

Anyone nearby that has AE? They could recalibrate the speedo for you. Or you could go to Ford to have it adjusted. But for 1 mile off, I probably wouldn't worry about it...

***ju015dd*** · #5 (**permalink**) 12-14-2009, 06:00 PM

Quote:

Originally Posted by layson

Anyone nearby that has AE? They could recalibrate the speedo for you. Or you could go to Ford to have it adjusted. But for 1 mile off, I probably wouldn't worry about it...

thanks, fig it wasn't much just wanted a second opinion.

coot1 · #6 (**permalink**) 12-14-2009, 08:58 PM

If your stock tires are 265/75R16 your speedometer should read about 57.5 when you are actually going 60mph. Your odometer will also be off by the same amount. Say for every 5000 miles you travel your odometer will only register about 4788 miles.

***ju015dd*** · #7 (**permalink**) 12-15-2009, 12:49 AM

thanks

**Hank** · #8 (**permalink**) 12-15-2009, 01:57 AM

You can find "calculators" online that will do the math for you, but you can also just calculate the circumference difference. 35s changed mine 7%. I would just add 7% to the miles driven when calculating mpg. I recently discovered that my AE would calibrate the speedo and now it it dead on!