Can 285's give you better highway mpg?

right now i have 265 mickey thompson mtz, and when i get to the wear bars i will change the tires. I've been doing research on tires and i was thinking of going to 245, i'm deciding between bfg's long trail and rugged trail. So will the 265 to 245 give me an increase in mpg because of less friction or should i stay at 265?

Thanks for your help

 

245s will likely mean less rotational inertia (usually but not always, altough the exceptions usually tend to be racing/performance tires), which would translate into a little better acceleration/braking and maybe some improved mpg depending on how your driving style adapts to that.

They will be almost an inch narrower than the 265s, so you could have traction/sinking issues if you drive on softer surfaces and you'll probably want to run a little higher tire pressure, meaning you'll also want to check the pressure a little more often since the TPMS is calibrated for the psi of the stock rubber (I run my RX8 at 32-34 psi on 235s and it weighs about 70% of what a 2nd gen ext/access cab does). Be especially careful if you get tires with reinforced shoulders; in my experience those ones don't bulge noticeably when the psi gets low and I had my outer sidewall completely separate from the tread in the middle of the freeway once when I got neglectful.

Also, if you haul much in the bed you'll want to stick with the wider tires to keep your load capacity up.

Finally, you'll give up a little grip when cornering with narrower tires, but with the geometry and suspension of a prerunner that's probably a non-factor since the truck may be likely to roll over before skidding out (unless you're power-sliding, but that's almost impossible to do with Trac/VSC activated) on dry pavement.

One way or the other, a step or two in either direction on the tire size isn't likely to laed to a drastic change in performance or fuel economy, though.

 

Thanks for that info. i'll probaly just stay with 265 since that's what i have now.

Is 265 stock on a 2005 v6 AC Prerunner, or is 245

 

My 2010 TRD offroad came stock with 265/75R16s and I think the sports come with 265/70R17s not sure about the SR5s/regular PreRunners but I think they're the same size as the offroad pkg.

This probably hasn't changed during the run of the 2nd gen which started with 2005, and if I remember correctly the 1st gen prerunners came with 31.5x10.5 tires (which are pretty close to a 265/75R16).

One thing to keep in mind if you go smaller is that your speedometer will read a little high and your odometer will run up miles a little faster since they come calibrated to the rev/mile rating of the stock tires (and if you go bigger the speedo will read a bit low and the odometer will undercount actual miles traveled for the same reason), most tire manufacturer websites or datasheets should show a revs/mile number in the specs. This calibration should be adjustable in the computer, but I'm not sure if you'll need to get it done at a dealer or if the tire shop can do the fix.

For example, the BFG site shows 654 for the 265/75R16 and 682 for 245/75R16, which means that without an adjustment your speedo would read 63 when you're really going about 60 and the odometer would count about 105 miles for 100 miles actually covered (this could lead to the impression of improved mpg as well since you'll think you've driven 5% farther than you really have) unless you get the gauges re-calibrated. If you don't haul much or drive super-aggressively you could consider going to 235/85R16s which have a rev/mile of 656 which puts the difference from the stock size tires within the margin you'll normally vary due to temperature/pressure variations and tread wear.