Same size..how much will weight impact MPG?

So i've already decided on a 17x8.5 wheel with 265/70r17 SL tires.

Wheels I am considering:
KMC Impact OL - 25.1 lbs
Method 305 - 29.5 lbs

Tires I am considering:
Falken Wildpeak AT3W - 46.5 lbs
Nitto Ridge Grappler - 43.41 lbs

I'm trying to decide which combo would give me the best mpg if there is any difference. THe lightest combo is the KMC plus Nitto = 68.51 lbs and the heaviest is Method plus AT3W = 76 lbs. This is a pretty big difference in weight. So my question is, even with everything being the same size, how much of an impact if any will the weight difference cause?

 

It will impact your MPG's, not a lot, but enough for you to notice. You'll lose (This is an estimate, not an exact number) 1 - 2.5 MPG's.

The more weight you add, the more rollingresistance you'll have. @hiPSI Can fully explain the science behind it if you want.

 

Stick with any C rated tire and you will barely notice. Maybe 1 - 1.5 mpg. If you step up into any real AT truck tire your weight will be in that range if not more if you go to E rated.
So relax and enjoy!

 

Does the rolling resistance only come into play when accelerating and stopping? There was another thread in here where they switched to a 10 lb lighter tire and no change in mpg.

 

Im sticking to the SL versions

 

Real world applications will very seldom provide you with lab test results, hence no change even though he ran a 10 lb lighter tire.

Rolling resistance loss will happen when adding weight, but the biggest penalty will come from accelerating the additional mass he is adding with the wheel and tire. (google unsprung weight)

This penalty really only happens when driving around town and lots of stop/start at lights and intersections. Your engine has to develop more power to accelerate the heavier wheel and tire combo, meaning it will require more fuel given the same rate of time. On the interstate, the heavier wheel and tire does not need to be accelerated from a standstill so the penalty is much less.

Now, how much of a penalty? With all things considered, around 10% for going for a heavier wheel and tire. An additional 10% for lifting. An additional 10% for hanging a bunch of weight on the truck. That is my rule of thumb.

Even the tread pattern will make a difference in efficiency, so choose wisely. Do I want to look really cool? Can I afford to look really cool? There are reactions for every action!

 

I went up from stock 30" at 53lbs to 31" falkens 67lbs (wheel and tire) and lost about 1-2 mpg after factoring in the speedo difference... around a 5% loss so not much.

I even bought a stock set of wheels and had them back on for a few days, wasn't worth trying to get the 1mpg back...

 

Hmm I wonder which tread has more rolling resistance between these 2 tires? The Falken's might be heavier but what if it has a tread with less resistance? Let's say I go with the lighter Nitto's, I still prefer the Methods even though it's 4.5 lbs heavier. I really can't make a decision.

 

See this is what I mean by every case is different. Was it the same tire and just bigger? Most would say 14 lbs per tire is a significant difference but you only lost 1-2 mpg. And here I am thinking about choosing my 2nd choice wheels because its 4.5 lbs lighter.

 

Those AT tires you mentioned impact a lot your highway mileage, I lost about 2 mpg going from stock to falken AT tires even keeping wheel weight the same

 

I went up to a 31 inch tire (255/70R17 from a 245/75R16) but I had to factor in that my speedo was about 5% low to begin with from the factory so my mpg wasn't really as high as the screen said. If I went by the screen I'd have lost about 3mpg.

That said go for the wheel you like as 4.5lbs per corner you'll never notice. I've been driving around on my falkens for a year now and I had bought factory 245s from someone to get my mpg back and figured the truck might even feel more peppy shedding 14lbs per corner... nope... just more squirrely with the street tires and my 3mpg back on the screen which meant as I said really 1-2mpg.

I'm nerdy so I went and calculated how many gallons I'd burn with 23mpg vs 20mpg as worst case and I'd save about 200 bucks a year driving 6k miles at $5 a gallon...

That's when I said screw it and sold the smaller wheels and went back to what I like. Safer, cooler looking, and if I want to have fun, I now can.

And I can't feel any difference driving around.

 

I’d go Nittos, look way better than the Falkens and go with the Methods for wheels.

 

yeah I do like the look better but now I’m reading the nittos aren’t great in the rain. So many differing opinions. I’m wondering if most AT tires suck in the rain after a certain number of miles maybe the first 15-20K.

 

yeah I’m gonna go with the methods. Do you use an app for calculate mpg or go off the dash reading?

 

Standard load tires look goofy when they are installed on wider than factory rims.




This is an example. You get this bulging effect on the sidewalls, rather than the flat firm look. They are valid for up to 9” rims but I always preferred how they look on 7.5”

it’s all preferences, just sharing. Buy what you like.

 

T

People definitely have opinions on tires, I’ve ran KO2s for 9 years and really like them. Never had an issue with rain, I live in BC and we get rain storms and snow storms. I do have a canopy so that does add a couple hundred pounds all the time in the back. If you drive like a normal person and not a nut job you’ll be fine with pretty much all the AT tires.

 

Rotational inertia. The heavier combo will take more energy to spin up. But once it's spun up, has more energy. So if you spin them up and slow them down with the brakes that energy is converted to heat. Do that a lot (stop and go, braking instead of having adequate buffer, etc), and you see a loss in MPG.

If you spin them up and you are on the highway, that extra energy doesn't get repeatedly disipated as heat. You won't see much of a loss in MPG.

Rolling resistance and the weight of the tire are not really related. Rolling resistance has more to do with tread pattern, compound, tire pressure, and construction. Unsprung weight has more to do with the ability of the suspension to dampen things.

What you are describing is rotational inertia.

 

uR=F/G
I also remember my audience when explaining things. Everyone here is not an engineer.

 

I did not know the rating affected the size of the tire. The wheel I want is 8.5 inches wide but def dont want a stretched look.

 

Theoretically speaking once they are rolling at speed it shouldn't matter that much, your loss will be from acceleration from a stop to a steady speed, not from maintaining a constant steady speed.