I got the best mileage with the needledick 245 radials, about 18 around town and 23-25 highway...truck was also stock. Year later, 3" straight pipe and an air filter, with 33x12.5x16.5 TSL Thornbirds, range D I believe, which were a pretty agressive tire killed the mileage. Only could get 14/17 at best, they were kinda squishy, and WIDE. They always rubbed in the front on a somewhat sharp turn.
Now I'm running 33x12.5x16.5 (I believe close to 315, maybe a bit taller?) Kumho Road Venture A/T's, similar to BF mud terrain, at 50 PSI (max rated) and the rear doesn't squash at all, front just a bit, not enough to notich while driving. I'm getting 16/21 now, with 4" exhaust with that aeroturbine straight through muffler and a 8-10 ground plate. Best part was the price, they were I think $130 each, and they wear like iron, so far.

 

i think i'm gonna try em.. 315's that is,, has anyone run 295's?? how tall are they??
what hp are the F1 mach 1.6's rated at??
and what would be a good turbo, to go with em??
i'd like to have a truck that can dual duty.... be getting mileage on the highway and still be the weekend he$$raiser

 

I picked up almost 3 mpg with 315's. It looks killer and the engine turns a bit slower at speed.

 

I lost 2 MPG going to 315's. I went down to 305's, took out the lift and got about 1.5 MPG back.

 

So, I'm going to hijack this thread rather than start a new one. I've got similar questions regarding mileage, wear and tear on the suspension, power, etc. My current tires are 265/75/16's and are almost due for replacement. A friend of mine works for a guy who just swapped on newer, bigger tires and wheels on his 3/4 ton Chevy. What he took OFF were BF Goodrich 315/75/16's mounted on Weld aluminum wheels. The tires have maybe 60-70% tread life left so they're not brand new but not too bad, either. He says he'll sell the whole set of 4 wheels + 4 tires to me for $450. Now, I wanted to go from the 265's to some 285's but I can't hardly pass up $450 bucks for rims AND tires. I've seen lots of pics on here of guys with 315's on their trucks and granted they look NICE but will I regret them when it comes to suspension wear and tear, mileage, power, etc.? I've got a 2" levelling kit, 5-speed, 3.54's and the only performance mods are drop-in air filter and 4" exhaust.

 

I've run 265-75/16, 285-75/16, 295-75/16, and 315-75/16 on rigs with 4.10 gear ratio and 3.54 gear ratio. I travel 173 miles each day, and hand calculate fuel mileage.

The 3.54 gear ratios best fuel economy was with the 285s. I didn't notice much performance difference between the 265s and 285s.
Both the 295s and 315s have a noticeably bad impact on performance and fuel economy.

The 4.10 gear ratio worked great with the 315s. RPM on the road at 75mph was still a touch high at 2100rpm and seemed to be just a little too high for best economy.

The weight of the larger tires (295s and 315s) also makes it harder to get rolling which really dropped fuel mileage in town. The larger tire really seemed to proportionally look better though.

 

The 315s on stock rims also rubbed the OEM control arms. The turning radius got big enough that it was a two step forward/reverse effort to get into parking spots. With after market control arms (about a 2" diameter tube), the rubbing was only at near steering lock.

 

I also should have mentioned that, with the installation of the 315's, I was finally able to find a use for first gear besides pulling stumps. Starting out in second gear as I had with the stock tires caused the engine to bog a little, so I began starting out in first gear - problem solved.
Still, I would have liked to have tried those tires on a truck equipped with 4.10's.

 

315's with 3.55 gears will hurt your mileage just like everyone else is saying. But the biggest killer on the freeway that hurts mileage is speed. The best mpg can be had under 70mph. If I keep it under 70 I can get over 20mpg with my 315's but go over 70 and it drops quite a bit especially the closer to 80 I get.

 

Toyo's list for $329.00 in that size. Express tire made me a price of $289.00 yesterday. You got the deal of the century or somebody made a mistake.