35” tire recalibrating speedometer?

[Kanesf150]

I recently leveled and installed 35” tires on my 22 f150. Is there a service ford can perform to allow my speed and mileage to read accurately? I’m about 2-3 mph over. Is it something as simple as a wheel speed sensor? TIA

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[NDakBoom]

I recently leveled and installed 35” tires on my 22 f150. Is there a service ford can perform to allow my speed and mileage to read accurately? I’m about 2-3 mph over. Is it something as simple as a wheel speed sensor? TIA

If you're adept at forscan, you can just change the circumference setting. I have 295/70/18 and had to use 2609 as my setting to dial the speedometer in.

 

[fgutz3rd]

If you're adept at forscan, you can just change the circumference setting. I have 295/70/18 and had to use 2609 as my setting to dial the speedometer in.

I managed to change the circumference with forcan. I have 35/12.50r18 on my truck Really heavy tires and it didt do much. I used to 5 miles over now im about 2 to 3 miles under

 

[NDakBoom]

I managed to change the circumference with forcan. I have 35/12.50r18 on my truck Really heavy tires and it didt do much. I used to 5 miles over now im about 2 to 3 miles under

I had to use a number that was not my actual circumference.

 

[fgutz3rd]

I had to use a number that was not my actual circumference.

Hmm. May I ask what tires you are running and what your final number was

 

[NDakBoom]

Hmm. May I ask what tires you are running and what your final number was

Falcon wildpeak. 295/70r18. Believe my final number was 2609. Ali I did was calculate the percentage my speed was off by comparing phone app to what pickup said and then either add or subtract that percentage to the tire circumference. Took two tries to dial it in.

 

[fgutz3rd]

I’m not that good with math. I have 35/12.50/18 tires and my number 2794 and my speedometer is off by 2 to 3. Goes back and forth according to phone app I am using and other online apps

 

[Je1279]

I recently put 295/60R20's (33.9") on my truck and had to use the circumference of a 32.2" tire in Forscan to reflect the correct speed on my speedometer.

 

[hotrodmex]

Rolling diameter would technically be lower than the spec diameter, since when weight is applied the tire squishes. The "correct" way to measure would be to mark the tire where it touches the ground, roll it forward one revolution, then measure the distance.

I'm pretty sure this is why everyone has to lower their calculated measurement.

 

[Je1279]

I was recently wondering if the smaller tire circumference would result in inaccurate odometer readings. However, this afternoon, I confirmed that the odometer is calculating mileage correctly using a GPS app.

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