Will mileage be inaccurate with wrong tire size?

[catskills837]

So I use my stock wheel/tires for winter and I run my KO2s in the summer which are quite a bit larger (34s).

I used ForScan to adjust speedo for the larger tires but have been lazy to readjust for putting the stock back on, my speed is off 2-4 mph at freeway speeds, the speedo reads 75 when I’m really doing 72.

Does this mean my truck thinks I put 75 miles on the odometer when I really put only 72 on? I imagine years of doing this could make it actually pretty off?

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[Oxford_Powerboost]

That’s correct, your odometer will technically be wrong

 

[emag1286]

Plenty of Forscan tire calculator adjustments out there to fix this. If 4x4 don’t forget to reset all adaptations on the pcm, clear adaptive transmission tables on the tcm, reset all adaptations on the tcm, and drive it for a few miles to relearn the shift points on the bigger tire sizes. That’s how you avoid the 4wd maintenance light.

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