Hybrid fuel efficiency with bigger wheels

[MavDaddy]

So I understand that a bigger tire effects fuel efficiency but does the same size tire with a bigger rim also negatively effect it?

For example: Lariat comes standard with 225/60r18. If I change that to a 225/35r20, will mpg take a hit? Same size tire (minus the added width of an 1 1/2" - 2") different size wheel. Gotta have my cake and eat it too

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[BDennis]

Get that larger tires might positively impact mpg, but watch the weight as this is spinning mass, not simple weight.

 

[BMCGC]

The three factors I see are rolling resistance, mass and frontal surface area.

Skinny hard tires vs fat soft tires. Which takes more energy to roll into a 70 mph headwind?

 

[Darksider]

Don't listen to these spinning mass crazies. The mass will be the same as anything you add to the cab since a wheel is balanced. Out of balance and then spinning mass comes into play.

I wouldn't get the tire size you wanted without calibration speedo though. It is going to say you are going faster/futher then you actually are .. For example speedo says 70mph you are actually going 64mph.. Or odometer says you went 100 miles which you actually only went 91 miles.

 

[JASmith]

Yes, but its one of those things that while true depends on "to what degree" if its even relevant or not.

The larger the diameter of the wheel, the further the wheel hub weight is from the axis of rotation, meaning it takes more force to spin it up. So a larger wheel should in theory negatively impact fuel economy, even if the weight doesn't change, because the weight that exists is now further from the axis of rotation, like trying to spin someone in an office chair that has their legs tucked in vs stuck out.

But since fuel economy is primarily affected by what the vehicle is doing most of the time and most of the time its not accelerating, and a +2 isn't that massive, its unlikely you would measure anything significant. You might feel a slight reduction in maximum acceleration, particularly since you often gain a some weight going +2 in size, and ride quality though.

Skinny hard tires vs fat soft tires. Which takes more energy to roll into a 70 mph headwind?

In this case though, both are skinny tires, and lower profile tires aren't necessarily softer or harder. It would depend on if you're putting on say an eco tire vs a performance tire.

I don't think the profile of the tire inherently changes fuel economy because BMW put rubber band tires on its i3 that they designed to maximize its range where every little bit counts, and many others like say Hyundai with their "blue" line of hybrids that get higher fuel economy than the standard models usually have smaller wheel higher profile tires.

 

[BMCGC]

I'm sticking with oem sizes, if I had an EB and didn't care about mileage, then maybe.

 

[Dechion]

So I understand that a bigger tire effects fuel efficiency but does the same size tire with a bigger rim also negatively effect it?

For example: Lariat comes standard with 225/60r18. If I change that to a 225/35r20, will mpg take a hit? Same size tire (minus the added width of an 1 1/2" - 2") different size wheel. Gotta have my cake and eat it too

Not sure if you are going for bigger overall, or just increasing rim size and going more for the "rubber band" tires.

I compared the ones you listed and they are actually smaller despite being on a larger rim.

A bit of poking around showed that a 235/45 R20 has nearly the same outside diameter to the factory tires with way less sidewall. Its also about a half inch wider, but probably doable with proper offset in your rims.

That should get you the 20" rim look without messing too much with your fuel economy. As an added bonus the speedometer will still be accurate.

 

[MavDaddy]

Appreciate all y'all's input! Will probably end up getting 20s if my wife let's me

 

[Dechion]

Appreciate all y'all's input! Will probably end up getting 20s if my wife let's me

I'm probably the odds one out, but I actually would have preferred the 17" tires for mine instead of the 18" its coming with, but I'm too damn cheap to swap them out, lol.

 

[Dechion]

Damn, those images are huge in my earlier post. Phone screenshots bigger than the phone itself, lol.

 

[MavDaddy]

I'm probably the odds one out, but I actually would have preferred the 17" tires for mine instead of the 18" its coming with, but I'm too damn cheap to swap them out, lol.

Im with ya. The XLT and FX4 wheels are leagues better looking than the standard Lariat...

 

[Nightowl]

I'm probably the odds one out, but I actually would have preferred the 17" tires for mine instead of the 18" its coming with, but I'm too damn cheap to swap them out, lol.

Same.

 

[Clinton]

So I understand that a bigger tire effects fuel efficiency but does the same size tire with a bigger rim also negatively effect it?

For example: Lariat comes standard with 225/60r18. If I change that to a 225/35r20, will mpg take a hit? Same size tire (minus the added width of an 1 1/2" - 2") different size wheel. Gotta have my cake and eat it too

The cake might not taste as well if your warranty is voided.

 

[MakinDoForNow]

Not sure if you are going for bigger overall, or just increasing rim size and going more for the "rubber band" tires.

I compared the ones you listed and they are actually smaller despite being on a larger rim.

A bit of poking around showed that a 235/45 R20 has nearly the same outside diameter to the factory tires with way less sidewall. Its also about a half inch wider, but probably doable with proper offset in your rims.

That should get you the 20" rim look without messing too much with your fuel economy. As an added bonus the speedometer will still be accurate.

So would 35 or 45 sidewalls on 20" rims require run flat tires in order to protect the 20" rims?

 

[TSAINTS1115]

So would 35 or 45 sidewalls on 20" rims require run flat tires in order to protect the 20" rims?

No. You can bend a rim no matter what tire is on it.

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