I know these this thing isn't a Toyota Prius, but I seem to have taken a big hit on my mpg (bigger than expected) when I put my new tires on and was just wondering if others had experienced the same?

Before, with my armor, roof rack, light bar, etc., I had dropped down to about 11.5 mpg around town and perhaps somewhere like 14.5 on the freeway. After stepping up to 32" BFG KO2s, I have dropped down to around 8.5 mpg in town and 11.5 - 12.5 on the freeway. Now, I'm in the northern VA area, so when I say "around town", I mean a stop light every few feet. But still, that's quite a drop! Anybody else have the same experience? Just curious. Thanks!

 

I'd say that's believable depending on how you drive it and the elevation/hills/etc.

I was running 32" Duratracs (275/65-18) which are comparable to the KO2 and if I was careful on the highway and drove the speed limit at sea level on flat terrain I could do better than that. Maybe 15mpg if I was lucky. 14 was more common as I remember.

With my current 33" (275/70-18) STT Pros I'm lower still. Now 14 takes good conditions while 12.5-13 is more common when driving easy at the speed limit. Last weekend I pulled into a club gathering and announced with some pride I had averaged nearly 15 mpg on the drive down (about 35 miles of 50-55mph 2 lane followed by 15 miles of 65-70 interstate all flat/sea level)

If I drive it like a 'normal' vehicle, i.e. 75-80, I'll be lucky to see 12 even on flat highway at sea level.

I have more armor/weight than you based on your sig line, so that's a factor but not that big a deal. Rolling resistance of the tires, weight of the tires, and air resistance from bolt-ons like a rack are the mileage killers.

What pressures are you running? I'm assuming you went with the E-rated BFGs. You'll want to run higher than stock pressures in them on the highway. I run 50f, 52r in my current tires and it makes a noticeable improvement.

As for city driving, I just try to avoid that. I've not spent enough time with this rig in the city to know what it would do to the mileage over any distance but it would be single digit I'm sure.

 

Hmmmm....I haven't checked in a while, but I'm pretty sure that I can get 18 MPH with my 32" MT/Rs running at 42psi. I don't have the weight you guys do. Just RS Sliders and Rasta skid plates.

I used to get 22 mpg though, so there is still a hit in terms of economy. These tests were between Seattle and Portland on I-5 and when "driving for mpg" I'd just go the speed limit and avoid any sudden acceleration or deceleration.

 

Yeah, my weight shouldn't be THAT high. I've got TF sliders and a Front Runner sump guard... all of which are aluminum. Dual battery system adds weight though as does a 12k winch on the front.

I'm currently running somewhere around 46psi on the front and 48-50 on the rear. I've been meaning to do a chalk test to see what it looks like, but just haven't had the time recently. Still, I doubt there's much room for mpg improvement there. Guess it sounds normal'ish if not a tad low though. Oh well. Houm, I don't know how you managed 22mpg. The best I was ever able to achieve was when I drove my car back to VA from SC after picking it up. I drove like a grandma and only managed 20mpg.

 

You have something else going on. I used to average 14-16 around town and 17-20 hwy with my 32.8's

 

Well, I did an injector and induction cleaning service not too long ago (not more than 15k miles). I guess it's been a while since I've changed the air filter, so I'll do that ASAP and see if results change at all.

Any other suggestions?

 

As for my 22 mpg: I reset the values once on the freeway at "cruise speed." I was driving barefoot and really trying to minimize rapid change. I did it more than once. That was done on stock sized Michelin Synchrones.

 

Out of curiosity are you using the actual odometer readings? With bigger tires it will show less miles than you traveled thus making your gas mileage less. You might want to check it with a gps to see how accurate it is.

If you're aware of this I'll offer my apology.

 

That's crazy! I never saw that sort of economy! When stock I could average around 17 or 18 if I was careful, though that was a long time ago and I only had the truck stock for a short time before the mods began.

 

Just saw the note about resetting after you got to highway cruising speed. That certainly helps.

I do need to correct my statement. I saw an average of 250 mpg over about 40 miles. Of course that was coming down a mountain....coasting almost the whole way.