Tires vs gas mileage

[kevfish1]

I just put some AT tires on my suburban and it looks like they are getting me 2-3 miles per gallon less than the previous tires which had a less aggresive tread. Is this normal or possible.?

[Scott K]

Are the tires the same size? Your speedo could be off with different size tires.

[kevfish1]

Yes, same size just a more agressive tread. Or maybe it is some other problem that happen to just start now after new tires

[Whoaru99]

Tires can have different rolling resistance so, yes, it is possible for a different set of tires to change fuel economy. 2-3 MPG decrease seems like a lot though but not really sure what the expected /typical effect might be.

Confirming air pressure with a couple different gauges would be good, then consider as well we're really just getting into winter and fuel economy always seems to take a hit with that too.

[Scott K]

Are you letting it idle to warm up? That is also a millage killer

[highlife4me]

Cold air is denser than warm air and increases drag. 2-3 MPG seems a bit much, but if you add together all of the variables, new tires, cold weather, increased idle times, winter blend fuel you could easily see that kind of drop in mileage in an average tank of fuel.

[kevfish1]

I am getting the gas mileage reading by looking at the instant economy on the dach as i am going down the hwy with the cruise is on after the vehicle has warmed up. With the cruise set on 60 I used to get 17-18 mpg. Now it reads 13-14 mpg

[MuleShack]

Tires can have different rolling resistance so, yes, it is possible for a different set of tires to change fuel economy. 2-3 MPG decrease seems like a lot though but not really sure what the expected /typical effect might be.

I've had different tires that "looked" different on the truck. Had some BF goodrich rugged trails that with 65 psi looked like they were running low on air. Now I have Michelin LTX AT and at 65psi they still look round. So this probably is what the above poster is referring to. I didn't really pay attention to gas mileage very much, but now with the michelin's i'm getting good mpg.

Verify that your psi is to the recommended levels in all 4 tires. EVERY time I had tires put on or changed out winter for old tires...the outfit NEVER had either recommended air pressure or the pressure was different in all 4 tires.

[fishing tech]

I am getting the gas mileage reading by looking at the instant economy on the dach as i am going down the hwy with the cruise is on after the vehicle has warmed up. With the cruise set on 60 I used to get 17-18 mpg. Now it reads 13-14 mpg

You can lose 3-5mpg with the cold weather. I drop 3mpg on my f150 and 6+ on my Taurus. But the Taurus I let warm up cause that sits outside.

One thing we were told during our "tire training" is that people may see an increase in mpg with new tire because technically they are bigger therefore covering more ground per revolution.

[fish_eat_sleep]

Don't look at the mpg reader. Not perfectly accurate. That thing could be 1 mpg off due to different tire diameter of the brand new set. Cold weather fuel with longer idle times could be 1 mpg. and rolling resistance of the more agressive tred could be 1mpg. thats 3! Check with a calculator and a notebook at the pump if you want to be most accurate.

[deadeye]

Cold air is denser than warm air and increases drag. 2-3 MPG seems a bit much, but if you add together all of the variables, new tires, cold weather, increased idle times, winter blend fuel you could easily see that kind of drop in mileage in an average tank of fuel.

This

[shizzy]

I agree with what has been said. When I went from 235/75/15 Highway treads to 31x10.5 AT's on my Ranger, I only dropped about a 1/2 MPG. So factor in the fact that my speedometer is reading a little slow now, that's probably 1MPG actual.

I drop another 1 or so MPG every fall once the cold weather sets in and they switch to winter mix.

[countyline]

I mix regular non oxygenated with reg oxygenated in the winter seems to help a lot. I don't get frozen gelled up gasoline lines also aids in MPG loss. Only down side is not every station carries it.

[MJ1657]

This is a little off topic but it addresses tire vs mpg.

On semis they rate a tires rolling resistance. I switched from some low rolling resistance to high rolling resistance tires on my Peterbilt and it caused my mileage to from a 6.5 average to 6.3

[Whoaru99]

I mix regular non oxygenated with reg oxygenated in the winter seems to help a lot. I don't get frozen gelled up gasoline lines also aids in MPG loss. Only down side is not every station carries it.

Around here the only non-oxy is premium. The pure gas gain in MPG over E10 doesn't offset the higher cost of the premium non-oxy fuel.

[Scott K]

Plus if your vehicle isnt designed to run on premium, a lot of times running premium will cause less mpg.

[delcecchi]

And besides, putting "off road" non oxy gas into a car is unlawful, as I understand it.