I just purchased a 2003 2500HD Chevy Duramax/Allsion, and noticed my odometer is reading low on the mileage. The rear end has a 3.55 ratio, and the tires are 285's 16". How much effect will these features impact my mileage and if possible can the car's computer be adjusted or re-calibrated? Any thoughts on this?

Thanks,

Jesse

I don't know how much the tire size will affect the mileage but, you can recalibrate tire size with a predator or a TechII I believe.

I thought the only gear ratio option for the D-max was 3.73s?

I went from 245's to 285's and my speedo is off about 7%. It doesnt really matter what rear end is in your truck as long as the speedo is calibrated for it and the size tires that are on it. As long as your speedo was right you just need to know what tires you started with and what tires you went to and find out what the difference is.

Jesse........read just a smigg'n, just a smigg'n. FYI, it's under search.

Usefull link.



While is says' Miata, it will calculate ANY size tire difference:

http://www.miata.net/garage/tirecalc.html

Its a 3.73. rear gear unless someone changed it aftermarket.