Pissed off about MPG after new tires

02 Prerunner 5VZ-FE 6cyl

I had two BFGoodrich ATs and two off brand ATs (stock 265 70 16) Iwas using for years since I bought the truck. I was getting about ~290 a tank with them. Ive got a shell on my truck as well.

I recently switched to Falken HTs (stock size). They ride much better, quieter, and smoother, but now I’m getting about ~220 a tank. I thought HTs and new tires would improve my mileage, what gives??

UPDATE: Hey sorry for the late reply. I used to have two stock BFG A/Ts and two aftermarket A/Ts on it from the previous owner, 265/70/16 stock size. The tires were so worn down Pep Boys wouldn't patch them. I had Falken Wildpeak H/Ts put on. They ride better than the worn A/Ts, but I'm getting almost 100 miles less per tank. I called the store and they said they've never heard of that issue with these tires. WTH???

 

What's the weight difference in the tires you had vs the ones you got put on?

 

This; size of the tire is one thing but you could have a different load range which would mean a heavier/lighter tire.

Let's not forget adjusting to the proper tire pressure as well.

 

If the Falkens are E load tires and your previous ones weren't, that could explain the drastic change. E load tires are significantly heavier and weight at the wheels makes a big difference in mpgs.

 

Unless we're all wrong and maybe you just picked up a couple of pounds since your last set of tires.

I know I'm not losing any weight lately...

 

Are they made in China?

 

do tires weigh less in say Colorado? Denver(ish) not the super high up there places

 

As a scientific principle, yes. Weight is dependent on gravitational constant and it's distance to the center of mass, so an increase in altitude does result in a decrease of weight.

As a practical application, lolz no. The weight change is so small that it doesn't matter one bit, especially if that advantage is more than offset by a less efficient fuel/air mixture.

 

all i know is from an earlier rocky mountain adventure i was getting 2 or 3 more MPGs on the current tires i have than i seem to get down river

so it VERY MUCH seemed to matter a little bit, or quite a lot! but heck if i know what was going on
but the extra tire weight can explain so much to my peesized brain lol

 

Haha.

As a general rule I do my best to turn off my internal MPG worrywart mode when on a road trip. There are way too many variables when travelling that it renders all comparisons useless. Your driving habits change, the stop/go action is different than from your daily commute, the hills are different, prevailing winds are different, as is the luggage weight... Sometimes Ive gotten fantastic mileage on trips, sometimes shockingly terrible. The causes of that are from too many different influences to measure.

 

Even if they say their the same size they could be bigger and your odometer is off now a bit? What I'm trying to say is maybe your old tires ran small for the size and the tread was all gone. Maybe the Falkens run big for the size and their at full tread, plus weigh a little more too. Last thought, have you tried putting more air in the new tires?

 

Falkens generally run very heavy on the range. I still like them for my fun tire set because they are very tough in my application and they are cheaper than other brands. I have street tires for mpg.

 

At highway speeds there is a small improvement in mpg at higher elevation, due to the air getting approximately 10% thinner every 3000 feet. It's easily lost in all the other noise that goes into real world mpg.

 

like others said:

need to know the specs on the new tires (load rating, weight, etc)

Seems like your old tires were worn. Less material = less weight.

For what it’s worth, I recently changed my wheel/tire combo from the previous owner and ended up saving 9 lbs per tire in weight. Combined with the wheel weight savings I’m looking at nearly 20 lbs total per wheel/tire.

Made a huge difference with not only drivability but fuel economy also (at least what the small sample size of data is showing)

 

BFG KOs are nice but heavy - I wonder what tires are a good compromise. Currently I have some heavy ass 8 ply mud terrains on in need of replacement. I get about 17 ( I think) but don't watch it too much. I think what others have said about the weight of the tire, width etc. will play some part in it. The bigger the tire the more rolling resistance they will have but you said you are stock size. What does your door sticker say stock is?

 

The Falkens are 39 lbs per tire in that size, which isn't huge, but I bet its more than your old ones.

 

One thing everyone has to consider is the diameter of the tire and how it affects the speedo/odo

I know when I am running “oversized stock” 31x10.5 r15 on my 98 that the speedo/odo run high and thus give me the impression of better fuel economy. 20-21 mpg mixed.

On my 04 I’m running 265/75 r16 which is bigger than stock size. But my speedo/odo are dead nuts accurate. So my 19 mpg is legit.

When I read everyone’s posts about their fuel economy my first though it, “how accurate is your speedo/odo?”

I know this doesn’t really apply to the OP’s situation because he replaced the tires with the same size (presumably based on his “stock size” quote). Unless his original tires were so worn out that the difference in diameter between those and the new ones were drastic enough.

 

i don’t want to sound like a dink but did you consider how much of that extra 2-3mpg was because of going “downhill?”

I know when I’m playing around in the mountains and eventually drive home to the front range, I’m always super stoked when I get 210 miles to the top half of the tank. I try to make myself forget the fact I’m driving from 10,000-12,000’ back down to 5500’