Low MPG help

I recently threw some new rims and tires on my 2017 SR DCSB 4 cyl AT, and I'm seeing more of a drop in MPG than I expected. My new rims are 0 offset 4.5" backspacing so the wheels extend about an inch out of all fenders now, and the tires are 265/75r16 so they are an inch or so larger or so, but I expected to only lose 1 mpg or so, but I'm getting about 17.5 mpg now. Almost all of my driving is city, though my daily work commute is about half highway, half city. I wanted to know if anyone else is getting similar to what I'm getting with a similar wheel set up, or if I'm getting fewer mpgs than I ought to be getting. Thanks in advance for the help

 

4 banger?

 

Yes sir, 2.7 liter. 6 speed automatic trans

 

What load range tire? How heavy are the wheels? Tire pressure? A heavy tire and heavy wheels will cause a dip in mpg.

 

you've added 2x size bigger diameter tire than engine/axle was designed to turn,and added extra unsprung weight for the little engine to push, this combo will have a definite effect on your MPGs. keep in mind the OEM Dunflops weight only 32lbs. per tire every pound extra tire weight equals 10 pounds x 4 tires roughly

 

Each corner is 65-75 pounds, not sure exactly, they're Toyo open country at/2 and the size reads as "LT 265/75r16", but I'm not sure of the load range. 32 lbs per tire

 

LT sounds like an E rated tire which will weigh more than the standard load P metric because of the extra layers of rubber in the tires carcass

 

Yeah, that's about what I figured, I know it's a little under powered for it. One thing to note is that I've never been able to get numbers in the higher end of Toyota's estimation of this trucks mpg (19-25) even when I had the stock wheels and tires on. I was getting 20 pretty much no matter what. I don't know why either, it was stock til now with the new wheels

 

Yeah, they're definitely much more tire than the wimpy ones it came with. Maybe I need a spolier!

 

Your magic dash doesn't know you got big tires.

Calculate by hand, then factor in your new speedo/odo error rate. You're recording less than actual travel.

 

a better approach is to utilize the stock p245/75/16 size in stead of going up in diameter and weight. using a tire like the Michelin AT2 p245/75/16 will give an aggressive look with minimal sacrifice to the engines performance

 

Lt come in different load ranges

 

Are you doing all your calculations right? Remember your speedo is off, which makes odometer is off. You have to figure all that into calculations, factory size to new size tire.

 

Most 16 inch tires are E rated I've found. Most guys go to 17 and get C rated. I know that doesn't help after the fact, but that's probably why you don't see many complaining about such a big drop.

 

Instead of shopping around, they buy new rims?

 

yes but they all will weigh more than a Standard load tire which doesn't help in the MPGs, extra weight=lose MPGs

 

got to remember the OPs truck is a 2.7l 4 cylinder auto trans not a v6, the v6 can handle the increased diameter and weight a little better than the 4 cylinder can because of its added power.

 

Tire selection in C is minimal in 16. Much more available in 17 from my experience.

 

Did you check the weight of each tire/wheel assembly before and after?

Two things will drop you, rotating mass and rolling resistance.... both would likely have increased. Ride height will hurt too.

What mileage were you getting before?

 

Oh, also, are you using the computer to tell you mileage? That's going to change with the larger tires.... it will be inaccurate. The distance you travel per rotation has increased, but the computer still thinks is the old distance per rotation.