Odometer off - Re calibration

[Tonyrodz]

Consider this:

Mathematically, a 265-70-17 tire is 31.61" tall with a circumference of 99.29" and 638 revs per mile. Doing 70 MPH with a 4-Speed in 4th shows the engine turning about 1775 rpms.

Using the KO2 tire as an example, it's tread depth is 15/32. So that applies to the above.

Now let's say the tread depth is 10/32, the tire is now 31.29" tall, 98.31 inches around and does 644 revs per mile. It also loses 1 mph in 4th with the engine turning 1775 rpms.

Not all tires of the same size are the same size either. And this can get more out of whack when different width wheels are used too.

You lost me at mathematically. I looked like a deer in headlights reading that.

Everybody's getting all mathy on me. Not a math guy

Yeeuupp lol.

 

[swathdiver]

All that just means that as the tire wears, it gets shorter and the speedometer reads a little faster then when the tires were new.

The OPs old tires may have been short to begin as some brands and models are and got worse as they wore down.

 

[adriver]

I'm just going to address the rest of the board then on here with this. Here's how I am looking at this...

This is OP's first and (basically) only post (other than the duplicate thread).
OP says they are "almost exactly 1/10th off per mile (which is 1/10th off), but never says how they know this.

All that just means that as the tire wears, it gets shorter and the speedometer reads a little faster then when the tires were new.
The OPs old tires may have been short to begin as some brands and models are and got worse as they wore down.

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According to OP, THE TIRES THAT WERE GIVING THE WRONG READING, WERE THE FACTORY TIRES.

UPDATE - I figured it out. I had to buy new tires and the odometer is calibrated to the exact size. Tire wear (my were worn but not to a level they were unsafe, just needed new) on your tires causes the odometer to be incorrect (kind of a, duh, comment) but who knew a 1/10th of a mile? Just seems like a lot over the life of a car.

Have you ever check your odometer to see if it's correct? I did and it's almost exactly 1/10th off per mile. I did the math for about 170K miles and that equals 17000 miles above actual. Anyone ever have their odometer re-calibrated? I have the same tires that came from the factory so no changes there. Very curious about re-calibration of odometer.

Yet somehow now, has put on a tire that is different from the factory tires, AND NOW it is reading correctly?? (even if I believed that, that would be backwards). Claims this is "too mathy", but somehow figured out its 1/10th of a mile off.

Everybody's getting all mathy on me. Not a math guy but can read an odo and it was 1/10 of a mile off. But... I do appreciate the input and ideas. Still kind of an interesting topic. I thought the deal was kind of interesting. What really got my attention, when I called the dealer and asked about re-calibrating. The struggled to talk with me and directed me to GM. GM got super sketchy on me like a touched a very sensitive topic. I think I did strike a raw nerve with GM since odo's are to be accurate buy law.

RE: my RPO codes - that was the first thing I checked before calling the dealer. Everything matches up and tires that were on the vehicle vs. now are the same size, different brand.

For some reason, OP has not said:
Whether or not, the reading was too high or too low.
What tire size or brand is for either factory or new.
Has not shared the RPO codes, even though they took the time to check them.

Claimed to figure it out, but went in to ZERO detail.

UPDATE - I figured it out. I had to buy new tires and the odometer is calibrated to the exact size. Tire wear (my were worn but not to a level they were unsafe, just needed new) on your tires causes the odometer to be incorrect (kind of a, duh, comment) but who knew a 1/10th of a mile? Just seems like a lot over the life of a car.

STILL shares ZERO detail about HOW they "know" its off. Yet somehow has figured this out based off the (incorrect) odometer???

Open to any other ideas/answers why my odo would be off 1/10th on my old tires. In fact, checked my odo RIGHT BEFORE I went in for new tires wondering if tire wear might have been the issue. On my ride, immediately checked the odo and BAM, I'm back at accurate.

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The more the OP writes, the less detail they give, and the more the possibilities contradict themselves. Something is not right with how the OP has presented this.
Frankly, the only thing I can come up with is that I think the OP is a 350lb, mom's basement living in, mustang fan boy troll. Or, some how the OP is trying to get the board to give them some kind of evidence (for something like a small claims' court), that the mileage is off, and therefor the vehicle's maintenance or value is not accurate, and that should have been taken care of or divulged by either the seller or mechanic... (I think that's enough for you see where I'm going with this option).

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[swathdiver]

A lot of people communicate this way Justin. It drives detail and analytical types crazy. I for one never believed the OP started out with his original tires. Maybe he thought he was running the original size, my guess is that they were at best 60 series when they should have been 70 series or something along those lines.

 

[adriver]

A lot of people communicate this way Justin. It drives detail and analytical types crazy. I for one never believed the OP started out with his original tires. Maybe he thought he was running the original size, my guess is that they were at best 60 series when they should have been 70 series or something along those lines.

Sure its a possibility, and the numbers would be near right if that were true. FOR ME, this just seems like a bunch of outlandish claims. The OP would rather keep us in the dark with all this missing detail they could have provided to help, then claims **** its all fixed. Sure it could be true. They could have noticed they missed something simple and didn't want to look foolish, BUT.... that's not what they said.. TWICE.

 

[SnowDrifter]

Unplug your odometer and drive it for a year


On the real: I don't think you'll find anyone who'd be willing to perform an odometer rollback. From a business perspective, it's unethical.

Since you've owned it since new, why are you waiting until just now to tackle the issue? Are you trying to sell it or something?

Have you confirmed that your odometer is off and not your speedo? What I mean by this is: Compare GPS speed with vehicle reported speed with your speedometer needle.

Going forward: your best bet is to calibrate your speedometer and call it a day.


Other thoughts: Tire sizes aren't always accurate. There can be a fair bit of variance between brands despite an identical size listing. My vehicle was reading 7% high on my last set. Current set is dead nuts even when referenced with GPS.