Went from 17" to 20"

Wesley · #1 (**permalink**) 11-09-2011, 11:32 AM

I have a 2011 6.7 and I changed from factory 17's to 2008 factory 20's. How far off is my speedometer going to be? Also I have a 3:31 rear end, so is my fuel mileage going to increase or decrease with the rim change? Thanks.

Was 245/75/17 now 275/65/20

Wesley · #2 (**permalink**) 11-09-2011, 12:10 PM

Hear are some pics.

Tempsho · #3 (**permalink**) 11-09-2011, 05:43 PM

245/75R17 ~ 31.5" total height
275/65R20 ~ 34.0" total height

That is roughly a 7% difference if my calculations are correct. For example, if your speedo was correct with the 245's, if you are doing 60MPH you are actually doing 64MPH with the 275's. To correctly figure out your economy (if you don't get your speedo recalibrated with the bigger tires) you have to add 7% more miles to the distance you actually travelled to get an accurate fuel mileage calculation.

Tempsho · #4 (**permalink**) 11-09-2011, 05:49 PM

BTW the truck looks much better with the 20's on it!

**mysticblu999** · #5 (**permalink**) 11-09-2011, 06:50 PM

Much, much better!

**Olee_Poole** · #6 (**permalink**) 11-16-2011, 06:51 PM

Quote:

Originally Posted by Wesley

I have a 2011 6.7 and I changed from factory 17's to 2008 factory 20's. How far off is my speedometer going to be? Also I have a 3:31 rear end, so is my fuel mileage going to increase or decrease with the rim change? Thanks.

Was 245/75/17 now 275/65/20

Is this a King ranch wheel? Or Lariat? Looks great btw.