MPG for tires

[WindomEarles]

I'm shocked to hear that people are getting 2-4mpg drops when changing to all terrain tires on the 4runner. I would expect a very small change if the same tire size was kept. Even going from a p metric to an lt tire seems like it shouldn't really impact mpg. What's the deal?

 

[Jtraskell]

I believe it is the tire weight difference which causes the MPG drop. I just heard a quote on TV in reference to a some show they were advertising, that 10lbs of tire is like 100lbs of automobile. The guy was saying this as he was "shaving" rubber off his monster size off road tires, trying to lighten the tiers weight. Be safe.

 

[rebelbowtie]

Went from stock P metric tires to LT265/70/17E BFG T/A KO and noticed a grand total of 0mpg loss. I even recently did a 900 mile road trip with my good friend of mine with my truck and his bone stock 4Runner.

Both are 2004 v8 4x4's loaded down with camping gear and mountain bikes, the only difference is he still had stock size P metric tires and I was running larger LT all terrains. We both averaged within .5mpg of each other the entire trip.

I'd think you'd have to jump up to a 285 to effect fuel economy that much

 

[desertred]

The primary reason for increased mpg is the additional tire weight that accompanies many A/T tires (particularly those with increased load ratings). Other factors that may influence the level of mpg reduction may include an individual's driving style and/or the terrain driven. I suspect that if you live in an area where there is a difference between summer and winter gas, that may also play a part, if the comparisons are not conducted during the same seasons. That said, having no mpg reduction switching from the stock tires to the BFG's is pretty phenomenal, as there is a 16 pound increase per tire with the BFG (E load range).

 

[rebelbowtie]

I think the rolling resistance of a larger diameter tire effects more than a few pounds do. My overall tire size didn't increase much, my other truck however I went from 245/75/16 to 315's and I lost 4mpg on average because that was a much larger tire.

 

[x67934]

Some folks who report significant drops may not be accounting for the the tire size effect on the odometer. A larger tire will go farther per revolution so the truck is traveling more distance than the odometer accounts for.

 

[mtbnole]

if the tires are the same size, then only weight and rolling resistance will be factors.

You know how they advertise "eco-friendly" tires? those tires are low rolling resistance, and although they are typically the same size as the tires replaced, they roll easier do to different tread patterns and rubber compounds. AT tires are heavier (my P-metric destination ATs are only 2lbs more per tire, but LT versions are sometimes 10lbs more per tire), and have tread blocking that is designed to grip on low traction surfaces, there by having a higher rolling resistance.

does this make sense?

maybe 1engineer will correct/suppliment my thoughts here

 

[03_4x4Runner]

From 4wheeler magazine. Tires and Fuel Economy - Four Wheeler Magazine

This was with same size tires, if you go taller or wider you loose more mpg.

 

[characterzero]

you nailed it...

if the tires are the same size, then only weight and rolling resistance will be factors.

You know how they advertise "eco-friendly" tires? those tires are low rolling resistance, and although they are typically the same size as the tires replaced, they roll easier do to different tread patterns and rubber compounds. AT tires are heavier (my P-metric destination ATs are only 2lbs more per tire, but LT versions are sometimes 10lbs more per tire), and have tread blocking that is designed to grip on low traction surfaces, there by having a higher rolling resistance.

does this make sense?

maybe 1engineer will correct/suppliment my thoughts here

1. weight
2. rolling restistance
2a - tread pattern
2b - rubber compound
3. profile/width & aerodynamic impact

weight is the largest factor, as you have to spin the tires and slow them down. they are unsprung rotating mass, which carries the biggest penalty to your power.