Does 1" require reprogramming?

[DaddyO]

On my ‘24 Badlands I went from 35’s to 37’s and went from 17 to 15 mpg running hiway speeds in Texas. In town getting 15mpg. I didn’t recalibrate my tire size and at 70 m/h am showing 74 on my gps. I have switched to monitoring my gps for speed but have to set a destination to use it.

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[jensht]

For what it's worth, the ABS and stability control are tied to the programmed tire size. So you may get premature or delayed reaction if you get yourself into a situation where either is triggered.

 

[ABorges]

I'd like to change the tires on my badlands to 285/75R17 which is about a 1" increase in diameter. I'm thinking that will be close enough to not require reprogramming as long as I don't mind a minor discrepancy in speedo readout. Can I get any agreement with, or an argument against, with my thinking?

If it is only 1" difference, your speedo will barely be off.

 

[Dirtrider]

I'd like to change the tires on my badlands to 285/75R17 which is about a 1" increase in diameter. I'm thinking that will be close enough to not require reprogramming as long as I don't mind a minor discrepancy in speedo readout. Can I get any agreement with, or an argument against, with my thinking?

I might be halucinating but I thought the Badlands came stock with the 285/70 -17 tires (at least in '22, the year of my Black Diamond). Or maybe I'm having a senior moment. My Black Diamond came with 265/70-17 and I'll be going to the 285/70-17 which is as wide as I can go on the stock 7.5" wide rims. I'm not planning to reprogram for the larger tire size.

 

[HPNQ420]

Same here. 1 mph difference.

i didn’t bother with reprogramming tire diameter.

so 70 mph on speedo is 71 actual mph.

Only difference on mine is i lost approximately 2 mpg

still love the change

Actually a 2 mph difference. I am 99% sure that the digital speedometer is programmed to read 1 mph high over the calculated value. (I checked at a bunch of speeds.) So 70 mph on your speedometer is 69 mph calculated, 70 mph displayed, but 71 mph actual.

(EU regulations require the speedometer to read high. The instrument I have on my HPN BMW is from Germany and the +1 km/h is built into the open source firmware in its case.)

So the "built-in error" helps you with mild increases in tire size.

Reprogramming is easy if you care. Unnecessary if you don't.

 

[Brian_B]

Thanks, that's a better calculator than the one i was using. I'm not concerned with the slight speedo/odo error, I just worry about upsetting some of the electronic Voodoo on the Bronco

The voodoo only cares if you have a low or dying battery.

Or spin your tires excessively in 4wd

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