Stock tire size MPG

Just curious what kind of MPG difference everyone saw between the stock tires and tires they've replaced them with. I'm not talking about with larger tires or a lift. I mean stock size to stock size. I haven't been able to find a thread like this.

 

No one?

 

I would think it would be the same. I don't see factors of why it would be different but there could be something I'm missing?

 

Different tire compounds and weights play a factor. Not to mention tread design, etc.

 

damn talk about splitting hairs..

i could try to comment on this, but i made other changes to my truck in stages, not just the tires. but here goes..

i did run E range tires in 265/65-17 , stock diameter, for about 3 years, and they certainly perform differently than the soft stock tires in SL or C range. but the differences mileage are not significant. E's are a bit heavier in that size, but being firmer they have less rolling resistance at 35psi+... it's really not so clear to compare.

 

My truck came with P265/70/16's.

When they wore out I replaced them with P245/75/16's. About 1/2" narrower, but same height.

Went back to P265/70/16's for the next set.

Then moved up to P265/75/16's for a time. They are same width as stock, but about 1" taller.

I'm now at 208,000 miles and have E rated LT265/75/16's on my truck that are 15 lbs each heavier than stock and 1" taller.

In the 13+ years I've owned the truck fuel mileage has remained exactly the same. My wife and I took a 400+ mile road trip last week and got 19.7 mpg.

All of those tires have a moderately aggressive All Terrain tread on them and are a relatively narrow tire and no more than 1" taller than stock. In 40+ years of driving I've never observed any difference in fuel mileage going to a heavier E rated tire as long as everything else is the same. I have noted a loss of fuel mileage with tires that are significantly wider than stock, and tires with aggressive mud treads. I have seen guys lose 2-3 mpg after going to a mud tire from a street or mild AT tire even in the same size.

 

It's not as much splitting hairs as you'd think. On my old truck I'd seen MPG changes solely from changing the tires by going to a slightly heavier tire. I've heard a rule of thumb which states that one lb of rotational mass is about 20 lbs of payload in terms of how hard the engine has to work. Multiply that by 4 and now you're talking 80 lbs for 1 lb heavier tire. Some tires of the same size can be 10 lbs heavier than the stock tire or more.

 

Comparing the same size tire but different compounds/weights, I'd say your right foot would have more affect on the MPG than the same size tire but that's just me.

 

That's the theory anyway. But, I use cruise pretty religiously so the only difference is how hard the motor has to work.

 

Ill try to remember to get to this in a few months. Ive got a 4 cil 5 lug on bald stock dunlops. Going to a semi agressive all season for the winter. I get 23.5 around town and 24.5 on the highwayn trips

 

agree. i am now on a consistent setup with consistent routes, and i run the same 31's E range at the same pressures so i can compare mileage day-to-day with how i drive. it's all about the throttle. mileage ranges from ~15.5 to 20. and that's on the same highway drives. the average seems to be ~17.5-19 for me. all throttle.

 

Im full throttle literally every chance I get. Hasn't seemed to change much. Although this past trip i didn't need AC and i think it was 25.4 which is insanely good.

 

Update:

I purchased Cooper Discoverer AT3 4S tires in the stock size and have lost about 1-2 MPG over the stock Goodyear tires. Still pretty good MPGs though. Most of my commutes are between 19 and 21 or so.