Which is the bigger mpg hit

On the same wheel, which do you think will affect mpg more? A 33.7" tall tire that weighs 60 lbs, or a 34.3" tall tire that weighs 57 lbs?

 

So close it would only be detectable in a wind tunnel.

 

Hit to MPG, gotta be the 33.7" 60 lb-er. That's more unsprung mass. But with the 3 lb difference compared to the 57 lb tire, that's pretty close to where it probably doesn't even make that much of a noticeable difference.

 

I can tell you based on my truck and personal experience. Moved from heavy 275/70-18 , 33.4 tires (wildpeaks) at 61lbs to 285/75-18, 34.8tires which are about 55lbs. Stop and go city traffic mpg stayed the same but any mixed or highway driving I saw 1, 1.5 mpg improvement. And more importantly, even with the taller 35 inch tires the performance felt snappier.

So that unsprung weight has a large impact. That's why lightweight wheels are used for racing!

 

3 lbs and 1/2” probably isn’t a deal breaker either way. I switched from roughly 33.6 to 34.3” tires, but the new taller ones are 11lbs lighter per corner. I can tell the truck feels lighter on its feet and the average trip mileage I’m noticing on my scanguage driving around lately seems to be a little higher (like 1-1.5mpg). That said it’s been warm this week so that may be helping. Haven’t taken a highway trip with them yet to compare that type of driving.

 

3 lbs is not going to matter.

What matters more is the width and the rolling resistance of the tread.

I went from a 315/70R17 KO2 to a 315/70R17 Territory MT. The Territory's actually run more like a 285/80R17 in actual size and I picked up almost 1.5 mpg and a noticeable difference in how spunky my truck was on the Territory even though they were the same OD or maybe slightly bigger.

Even though I was still on a 35" tire, its width was close to my factory 275's and the truck was getting nearly the same MPG as it did on the stock tires.

 

Wouldn't the mpgs be inaccurate until an accurate speedometer calibration is done?

 

March 14th? Tire height?...circumference?...Ironic that this particular thread was posted up on Pi day.

https://en.m.wikipedia.org/wiki/Pi_Day

 

Don’t tell that to the guys who install 37” tires on their brodozer diesel trucks and claim their truck now tows better and gets better mpg than when it was stock.