Odometer Slightly Off...

Hey all. We have a 2003 Xterra XE with 38k miles on it. We just bought it used from Raliegh, NC, about a month ago. We're extremely pleased with it, except for one tiny, niggling thing: the odometer is slightly behind real mileage, suggesting the tires are too big. This can't be the case, because it has the original tires still on it (265/70-16s), and they are even around 1/2 worn. What could the problem be? The car was in a wreck at about 20,000 miles, but it was purely cosmetic damage (the female driver hit a pole, requiring a new hood, grille, and bumper only), thus I don't think that could be related. When driving on the highway, you can reset the odo at a mile marker, and at the next mile marker, it will show just .9 miles travelled, and doesn't roll over until much later. This builds up, and eventually it's way off. We've calculated the fuel mileage based on the odometer readings and actual miles travelled, and there's up to a 10% difference. Does anyone have any ideas?

The factory odometer and speedometer are rarely accurate. Many owners found that by switching from the factory 265/70-15 tires (about 29.6 inches) to 31x10.50-15 tires (typically 30.7 inches) that their speedometer and odometer became almost dead-on accurate w/ GPS readings.

Isn't that a good thing? Your warranty just got extended 10%!