How many MPGs will I lose if I get larger tires?

I drive a 1998 2.7l sr5 4x4 extra cab. I have stock size tires on it now, no lift. I'm wanting to get some 31x10.50x15 soon and I've read that they'll fit but I haven't been able to find much about how many MPGs I'm going to have to sacrifice. Thanks

 

Depends on how you drive. Drive like your in NASCAR or Grandmother? It all depends

 

I'm usually pretty easy on it.

 

2.3

 

Probably 2-10 depending on use

 

I have a 99 SR5 5spd 4.30 rear. Running a 265/75r16(31.6x10.4). I usually carry around 300lbs of tools and shite. TG low pro front bumper, not very aerodynamic up front. If I keep my foot out of it I can average around 20 mpg highway. More like 14-16 sitting through traffic, it will drop off after 65+ mph(hand calc) Try to keep your momentum, shift at 2500 rpm and accelerate as slowly as the traffic behind you will tolerate.

 

yea

 

You'll lose about the % of the size difference.

Take a look at the Tire calculator

 

I have 265/75/16s and have noted the below (estimates only)

1-50 MPH: fine
50-60 MPH: shows +~2 MPH
60-70 MPH: shows +~4MPH
70+ MPH: shows +~6MPH

this done unscientifically with a GPS unit while driving. I see where my speedometer becoming more inaccurate during highway driving. The effect is clearly not linear and there is more to all this I am certain elsewhere but wanted to share my experiences.
I am very aware of the delta on the highway and have no plans to correct.

 

Not knowing this has saved me lots of tickets I am sure. I drove my last truck for probably 5 years before I finally realized my speedo was not accurate. At about 30 mph it started to be off. Just a mile or two, but up around 70 it was more like 6 to 8.

 

I got 265/75/16 and here's about how mine is...I checked with a gps.

1-30 is ok.
30-50 speedometer is about 5 slow.
50-65 speedometer is 8 slow.
65-up speedometer is 10 slow.

So if I'm driving 60, speedometer shows 52. I've checked this against two different gps units.

 

Shouldn't be much loss with 31"s. I have 33x10.50s on my 97 2.7 5spd 4x4 and I still average low 20s for daily driving mpgs.(during the summer, it drops to high teens with winter blends and cold weather)

 

At least 1. Everything I've done has knocked off 1 at a time.

 

Keep in mind you're running more miles than usual with those tires. More than is spooling up on your odometer, thus making the mpg's lower than you would think by a bit...not by much though i guess, if you're only jumping to 31's...

 

You'll also be turning more mass with larger tires. Some models are heavier than others. You have mass, rolling resistance, decreased torque.... it ads up. I went from low 20 to mid high teens. I worry more about getting going than mpg.

Speedo and odo will be off by a %. If your new tire is 10% larger in circumference you need to adjust everything else 10% as well. Thats why low speed the speedo ks almost correct and the error appears larger the faster you go. Regearing can fix most of the above.

 

What is your gear ratio? That will make a difference

 

I figure my mileage by hand taking the % change into account. Going up a size dropped me a MPG, lifting dropped me another. I got 16. Threw some stock 31's back on and went back to 17. Just saving up for another set of 265/75's E-rated though just because I like the idea of not getting flats on the beach (hard head catfish spines). I'm sure all kinds of things play a part but if you don't want to sacrifice mileage, keep it stock.

 

Depends on what your stock tire size was

Don't forget the weight of tires which truck owners ignore

My truck OeM came with 29inch 225 series

If I put 265/70/16 which most are almost 48lb I am adding 12lb per corner

Of course there will be mpg loss

Most BRO have no idea how to do math and how much loss will be not to mention unless you regear will be slow as heck

Good luck

 

That's what I expected, but my speedo was actually off when I had smaller tires and going up to the 33"s brought it back to where it's almost dead on with the GPS on my phone.

 

I count my tuck and put the tires and Rims on the nect day, I wonder if I would feel a different my mpg is 25mpg if I keep the foot of the gas, I can get a solid 21 if I keep it at 80mph