It's been a while since the last time I really checked my mileage and did a real test/check of my tires so I did it this weekend.
My Tacoma is a 2001, SR-5 extended cab, 2.7, Auto, 4x4, step-side with 31" Wild Country (TXR-265/75/R16) ,Elbow breather and other little none essential mods and running 87 "Stop and Go" gas.
The tires have #36 in front and #38 in back and I'm hauling myself and truck bed tool box full of tools for about #400 total extra weight.

Mileage at fill up was 79.078 and it took 15.699 to fill it.
Next fill up was .....79.263 for total mileage of 185. It took 9.407 gal. to fill it. .... 185 divided by 9.407 = 19.666 miles per gallon. Keep in mind that this is all town and mountain driving here in Clay county, WV.
I'm very pleased with the gas mileage .

To check the tires I went to the high school parking lot and placed a chalk line across the top of each tire and drove about 100'. The chalk was gone on the fronts all the way across and the rear was gone in the center but a little remained on the outside and inside edge tread and that told me they need to come down a little. Dropped the air down to #36 in the back and re-chalked them and drove it again. Perfect on all four tires! Just a little spring time checking
I LOVE MY TACO Lol, Mike

 

Thats sweet, I get 14-16mpg with 285s, now I am getting some 315's mounted today, and will be like 12mpg.. oh boy!

 

Before I got my Tacoma I had a 4x4,350, 3/4 ton Cev. Suburban raised 4" with monster tires on it and a 12,000 lb. Warren winch on front of it. That thing would go anywhere but it got about 10mpg also. Just like most chevs it started giving me problems at about 90,000 miles so I got rid of it.
When I seen the gas mileage I was getting with this Taco I was ecstatic! There is nothing I would like better than to raise this Tacoma and get the big tires and the whole off road deal but the truth is,....I just can't afford The gas prices.As of today it's $2.70 for 87. :pat:

 

I keep a pocket planner type calendar thing (1 month/2 pages) in my glove box and do that calculation EVERY time I get gas. If you do that, you'll begin to get a feel for how those driving habits, road conditions, maintenance issues, etc, impact your fuel mileage. I can usually tell after a few fill-ups when something is REALLY amiss...

 

actually, you have larger than stock tires.

265/75's are about 3.28% larger diameter than 265/70's. don't do the pure math on the numbers, but look at the actual tire specs and you'll see that you should be running a "30.5-inch" tire and you have a "31.5-inch" tire.

so, with 185 miles, you ACTUALLY traveled 185 * 1.0328 = 191 miles for 20.31 MPG!

 

Yep, that's pretty good mileage for that vehicle!

 

Thanks you guy's. I never was any good at math but did good in school at sex eduaction and off road driving, Lol.
Here is a good artical on checking your tires with great pics to show the chalk lines. I was told how to do this years ago by a friend who was a dealer in large truck tires.
http://toyotatruckworld.tenmagazines...rticles/31802/

 

Where are you at? You have Wild Country TXR's so I assume you got those from Schwab? I love those tires!

 

After looking all over for the tires I wanted (Wild Country) I found a place in Summersville, WV about 55 miles from me who said they could order them for me. It took about a week to get them and he charged me $125.00 each mounted, balanced and tax out the door. I was happy with that price!
There is only about 8,000 miles on them but they look like the day I got them
and I really like the ride. Great in mud, snow or rain and bad on ice