Size of tires

[yrraljguthrie]

I know the answer to this has many variables, but if you have driven for a while on one size tire and then switched to a larger tire did your mpg increase or decrease? Maybe include some variables like where you drive, the width of the tire, the engine, etc. What I've read says all these can affect the mpg especially the torque the engine can produce.

 

[ppine]

Your mpg should increase slightly with larger tires with a corresponding loss of power.

 

[brian42]

I would think that, all things being equal or larger, the increased rolling resistance and unsprung weight would translate into additional inertia to overcome...aka MPGs go down. Not to mention that the gearing and engine/transmission tuning was done based on the smaller circumfrence of the OEM-sized tire.

Even if you reprogram you speedo it's stil not going to be as efficient overall with the stock programming and stock gearing IMO. This doesn't take into account that you will be laying into the throttle harder because it will feel down on power (as ppine mentioned).

Most lager tires are going to Load Range E which are considerably heavier. Even if you already have an E-rated tire the additional weight adds up quickly, especially if you are going to a softer all-terrain type tire.

I've never oversized my tires and had my MPGs go up, it's always been the other way around.

 

[RamDiver]

I'd say the term 'larger' size is somewhat ambiguous to draw any specific or detailed conclusions related to mileage. How much larger than OEM and specifically, how much weight increase per wheel?

When I stuck 33x9.5 BFG Mud Terrain tires on my '87 Toyota extended cab (after a 3" lift), the mileage took a big hit. The lift didn't help the mileage but those BFGs were much heavier than the OEM 30" wheels.

The Toy had a 22RE, 4 cyl engine but being a standard transmission, it still made enough low-end torque to provide endless fun. I wish I still had that truck for winter driving and off-road entertainment.

.

 

[brian42]

Even when I went "+1" on my F-250 (265/75-16 to 285/75-16) I took about a 1 mpg hit. And that's with a diesel that could make the earth spin faster at 1600 RPM. The truck didn't drive any different since it had gobs of power down low but the fuel tank definitely drained a little faster.

 

[John Jensen]

Every time I've gone to a larger tire or a heavier stock-size tire I've taken a mileage hit. Every time I also recalibrated the speedo. If you go larger and don't recalibrate the speedo you'll see a mileage improvement but it is not accurate.

 

[RamDiver]

Even when I went "+1" on my F-250 (265/75-16 to 285/75-16) I took about a 1 mpg hit. And that's with a diesel that could make the earth spin faster at 1600 RPM. The truck didn't drive any different since it had gobs of power down low but the fuel tank definitely drained a little faster.

What was the actual change in tire weight?

The same-sized E-rated BFG KO2's are much heavier than Michlin Defenders, is my point.

If we're going to discuss mileage relating to tire changes, why wouldn't we include other important parameters such as weight and tread characteristics?

.

 

[Razzman]

It's all relative to how much bigger you go. If your going a lot larger then yes you'll see a mileage hit. A big increase in width and a larger contact patch can also affect it as well. I went bigger and re-programmed but kept it reasonable, 285/60R20 to 285/65R20 which is a 3% increase. I've noticed no difference in mileage or power.

 

[yrraljguthrie]

"I'd say the term 'larger' size is somewhat ambiguous to draw any specific or detailed conclusions related to mileage. How much larger than OEM and specifically, how much weight increase per wheel?"

Bigger-Larger or bigger relative to something else. Pretty simple. I asked about YOUR experiences. You would know what size tire you had and what size you moved to. I can't possibly know what size tire you had or what you changed to.

 

[gfh77665]

Typically any tire size change + or - from stock results in a MPG loss to some degree.

 

[Ramfanski]

Always a big mileage hit with larger diameter tires. Really heavy larger diameter Tires, a really big hit. Throw in an aggressive tread….massive hit.

This will be my first truck that I don’t go bigger on tires. I’m enjoying the great mileage…comparably.

 

[TestPilot57]

If MPG is your prime concern, stick with the stock P-Metric tires; that's why they come that way.

 

[Goose55]

I know the answer to this has many variables, but if you have driven for a while on one size tire and then switched to a larger tire did your mpg increase or decrease? Maybe include some variables like where you drive, the width of the tire, the engine, etc. What I've read says all these can affect the mpg especially the torque the engine can produce.

I wish I COULD have larger (especially taller) tires on my 2019 dually, but the rear clearances won't allow it

 

[Snowchief]

Every time I've gone to a larger tire or a heavier stock-size tire I've taken a mileage hit. Every time I also recalibrated the speedo. If you go larger and don't recalibrate the speedo you'll see a mileage improvement but it is not accurate.

Truth!

 

[TotallyHucked]

Generally speaking, whether you go wider or taller or both, you'll see a drop in mileage. I've done it many times in the past. The most extreme was my '06 Sierra I bought with 74k miles. It had a 5.3, 4L60 and factory 4.10 gears. With the light 17s and P-metric 265/70R17s, I saw 21-22hwy and ~17-19city. Once I put the level kit, 20x9 GM replica wheels and 305/55R20 E-load Nitto Trail Grapplers on it (77lbs per tire ), it got 12 no matter what. Uphill, downhill, unloaded, loaded, sitting in the driveway...12.

Now that said, it is possible to go up a size and not hurt your mileage if you keep tire weight similar or lighter. My ram has E-load Cooper Discoverer AT3s on it now in the stock 275/60R20 size and I average 17-18mpg on my commute. I plan to go up one size to a 275/65R20 Toyo AT3 and because those are ~5-6lbs less per tire, I expect no mileage change.

 

[TestPilot57]

Maybe this is obvious, maybe it was already addressed. But.

If you get tires with a larger rolling radius AND don't recalibrate your speed- odo-meter, your apparent MPG will go down. Because you will have traveled further than the odometer suggests.

Tire size with +X% larger circumference and no recalibration, you will show an MPG loss, simply because you went X% further than your odo shows.

A 35" tire is (roughly) 10% larger than a (stock) 32" one.

Lotsa ways to go from here, based on lotsa specifics.