can someone please tell me how to make my speedometer read correctly with my 33x12.50's????

 

WHAT YEAR is your truck? It makes a difference.
2WD or 4WD?
Manual or automatic?
What was the original tire size?
Was the speedo accurate before the tire swap?

 

What year truck? If has a cable driven speedo you need to change to a different ratio speedo gear. If it's all electric you can reprogram the speedo for different gears and tires. It's free and takes about ten minutes to do. Do a search on this site, i think instructions have been posted before.

-Jon

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2003 Mustang GT
URP Cold Air Induction
Flowmaster 40 Series Exhaust
Steeda Subframe Connectors
Steeda Strut Tower Brace

1992 F-150 Under Construction
Fully Boxed Frame
Tubular X-Members
6" Suspension Lift
35" Super Swamper TSL Tires
393 Stroker
Built C6 trans w/ manual Valve Body
Currie Enterprises Extra Heavy Duty 9" Rear

1996 Dodge Dakota Sport
Headers
Nitrous
1.7 Roller Rockers
Centerforce Clutch
Cowl Induction
U/D Pullies

No Money In The Bank

 

I believe it was 1993 and later that used the ToneRing in the Diff to caculate speed. If so, the fix is to reprogram the PSOM in the Cab. You will need to short out a wire under the Dash and then put in a new coefficient. This info should be availabe in the archives if you searh or on fords-trucks site.

My personal experience: I ran 33's for over 4 years before resetting the PSOM. I wish I had corrected it earlier cause after finally doing it, my engine not only ran better but got another 3mpg. And yes, I was factoring in the larger tire size when I did my fuel caculations....

-93 F150-

 

Whaynes, three more mpg! I need to fix mine right away! I went from 31" to 34.6" and yes speedo is way off. I hope the fix somewhere on this sight will include my 95 w/e40d. I thought I would have to hunt down the right speedo gear.