After reading all the reports of 2mpg drops when going from 31” to 32” tires I upsized anyway, even though that sort of drop would equate to over $600 in extra fuel costs over the life of the tires, more than the tires cost themselves! I was skeptical all along about such a huge drop, it just didn’t make sense, and in my case the instinct was right.

After 2 tanks the results are in.

1.) Stock GoodYear Wrangler RT/S with 15/32 tread = 30.7” diameter
2.) Bridgestone Dueler Revo with 13/32 tread = 31.9” diameter
3.) 3.76% increase in distance traveled per rotation brand new vs. brand new
4.) 4.54% increase in distance traveled per rotation considering the Wranglers were worn to 7/32”.
5.) GPS showed an increase of 4.94% in miles on odometer vs. real miles with Revos. Wranglers were dead on accurate.

Tank #1 on Wranglers = 16.48mpg
Tank #2 on Wranglers = 16.58mpg
Tank #3 on Revos = 16.25mpg
Tank #4 on Revos = 16.17mpg

Average on Wranglers = 16.53mpg
Average on Revos = 16.21mpg x 1.0494 correction factor = 17.01mpg!

An increase of 2.8% in fuel efficiency.

This is not even taking into consideration that the weather during last 2 tanks was much colder, and since I drive relatively short distances it impacts MPG significantly. With temperatures being equal it would probably come pretty close to a 4%.

 

Hmmm.......
Well I'm too tired to go over the math, but I will say that those numbers will probably turn alot of heads, especially since so many people say they lose MPG just going from 31's to 32's.

Myself, I just went back to stock 265/70 after a few month's on 285's, and I will say that my MPG has definitely improved.

 

That's awesome even if it is a little off! I haven't noticed any difference in my mpg from my switch 3K ago.

 

nice analysis

I just got new 31x11.5 and hope to get decent mileage as it is wider and may have more drag. Actual dimentions are 30.5 x 10.8

I hope I gain

peace Big Kahuna

 

Mine went down 1-2 mpg, but I went from street tires to much heavier/knobbier Wrangler MTRs. I may try some slightly less aggressive tires for a cross-country trip this summer and see if that improves economy.

 

If I go off my odometer which is incorrect now with the larger tires. It looks like I get less per mile. But in reality it's about the same.