Are these lowering my gas mileage?

Anything over 2k RPM on the highway hurts mileage. Dramatically so.

 

I'm guessing your driving habits are killing your mileage...

I have steel skids, steel bumpers, 33" heavy ST Maxx tires, a winch, a lift, and re-geared to 4.56 gears (which forces higher RPMs) and I'm getting better mileage than you.

That being said most of my commute is constant speed (70-80mph) so I'm not constant stop and go.

 

This. Also. What PSI are you running, are you more city than highway miles, how new are your plugs, how recent was your last oil change, do you run conventional or synthetic?

 

#1, figure your fuel mileage, you can't tell anything with the info you have provided and I bet you are getting more than 13 mpg.

#2, a Tacoma won't get much better fuel mileage than most 1/2 tons anyway. Expect at most 3 mpg better. And this should be expected. The towing and carrying capability of most Tacoma's is a lot closer to 1/2 ton than most think. The older 1st gens with 4 cyl engines got significantly better fuel mileage, but with very limited towing and hauling capability. You can't have it both ways, if you're going to have a tacoma capable of towing 6500 lbs it ain't gonna get much better fuel mileage than a 1/2 ton capable of towing 7000 lbs.

The shell doesn't hurt, if anything it will help some. That shell is about 170-180 lbs, but makes the truck more aerodynamic. Adding 180 lbs isn't going to hurt anything.

The tires may well be costing you about 2 mpg. The more aggressive treads have much more rolling resistance. Also LT tires are about 10 lbs heavier than P series tires and that hurts.

The truck in my avitar is an 07, with the same overall size tires and a shell. Put I stayed with P series tires and an AT tread pattern instead of an aggressive tire. I get around 17ish for normal every day driving and 19-21 mpg hwy depending on how fast I drive.

 

I have a DCSB 6 speed with heavy E rated 265/70r17 KO2's. I'm running about 17 mpg right now. An auto pre runner should be at least 2-3 mpg better with the same tires.

That said the fuel gauge isn't very useful. Down to a quarter on mine will only take 12-13 gallons to fill it.

 

ill bust out the calculator when i get to the end of this tank which should be tomorrow. I just bought the truck a few days ago from a dealer. What i do know is it was a one owner and has had all of its scheduled maintenance in its life so far

 

Problem with that is you don't really know if it was full when you started. The gauge may read full when it's still short of a natural cut off.

So while you are doing math (yea!) it may have the wrong numbers in the equation.

And again, is there a correction factor needed for tire size different than OE? A few % points is significant in calculations.

Don't put much stock in one tank. Keep records and make an average over several tanks.

 

How to accurately measure MPG and full tank range. I second the above post, do several tanks and get an average:

https://www.tacomaworld.com/threads/how-to-chart-fuel-mileage-range-etc.365941/

 

I have a DCLB TRD Sport 4.0L and a topper. If I stay below or at 2k RPMs I can get 20ish +/- on the freeway and 17 around town. Got 23mpg one tank in Idaho with flat roads and 55mph speed limit. I've got 265/70/17 tires and a 3" lift.

 

For what it's worth, here's some MPG information on my vehicle:

Average MPG w/o Leer 100R Cap: 18.2
Average MPG w/ Leer 100R Cap: 18.0

Stock size P245 tires the entire time (Dunflops or Michelin LTX MS2s).

 

^^ This here.^^

I think your math may be off like bill said. 13 mpg seems excessively low. I'm able to still get right around 18 mpg highway with 265/75-16 with slightly aggressive tread.

 

Toyota gave me a prius for a loaner when they did the frame coating on my tacoma. I have never hated a vehicle like I hated that thing. My truck gets crappy mileage.... So what. My motorcycle gets about 60 so it all averages out.

 

Doubtful.

 

The real question is do you like you Tacoma better than your silverado?

Hey, I noticed you said the silverado was 4x4. Why not go for a 4x4 tacoma?
What year Silverado did you have?

 

I did 25 mpg on the stock Dungflops on flat roads at 55 mph. If his tire is a P metric tire and not a heavy ass loaded rated tire I see it as doable. I haven't drive any 55 mph roads since going to my current tires.

 

So not with 270/65/17s (I'm assuming he meant 265/70/17) and not in a lifted truck with a topper.


Noted.

 

Driving style has a big effect. I drive like there's an egg under the gas pedal.....It helps.

265/75/16 load range C Goodyear Duratracs @ 35 psi. DCSB, 4.0/auto. w/3" lift. I routinely get over 20 mpg....IF I STAY UNDER 60 MPH.....

70 to 80 and it drops to about 16 mpg.

Don't over-rev....stay below 2K on the tach.

On a couple long highway trips on relatively flat interstate with speed set (cruise control) @ 65, I've seen as high as 22. Not common, but not impossible

A couple long trips @ 75+ mph, tires around 29 to 30 psi, and in general, driving it like I stole it....as low as 14.

I keep pretty close watch on mileage.....old habit.

Google "hypermiling" and study their techniques....You can increase mileage to well beyond 20mpg with these tricks.

 

Wow thanks for that info guys. My silverado was a 2004 1500 LT 4x4. I would have prefered a 4x4 tacoma but the 2wd will do fine for what I do. Occasional dirt and shallow sand by the beach/shore in lake havasu and the Gorman, ca ohv area. I used to have a peg leg 2wd silverado that handled this stuff fine so the tacoma should perform well

 

Just finished a 660 mile trip where speeds ranged from 74-79 the entire way. 265/75-16, 884s and AAL, 6 cylinder/auto, access cab, 4 wheel drive and 19.4 mpg. I drive about 15 miles a day regularly from work and back and have yet to get less than 18.