Tire weight VS Width

I currently have
265/75/16 Cooper at3 4s weight 41lbs

Was looking to replace with either

265/75/16 hankook dynapro atm's 37lbs
or
235/85/16 firestone destination AT's 39lbs but 1'' less wide and same height as 265/75/16's

I have a 2.7 auto so tire choices are more important to me over the 3.5 guys. I have added weight with a cap on back. Minor trails and camping is all i ever do, i did some digging but could not come to a conclusion. Both tires are less weight then what i currently have but does weight or width of the tire play more into the rolling resistance. Could also switch to a lighter wheel and save 3-5lbs but if the width of the tire will play more of a roll than weight id be better off with the pizza cutter.

 

Narrower would equal better MPG IMO.

 

There is not a direct relationship between a tire’s weight and it’s rolling resistance and manufacturers don’t publish rolling resistance thus it’s a crap shoot. In my personal experience I think you can assume an all-season to have the lowest rolling resistance, followed by a all-terrain, followed by a mud terrain. Load rating probably also has an effect as well as tire size.

I’ve never any good sources of info on this subject. Even in the bicycling world, rolling resistance is mostly a mystery, albeit there is a private individual with the appropriate equipment that has published rolling resistance results for several bicycle tires.

 

More width means wider contact patch means more rolling resistance.

 

Thats generally a good assumption, but I read a study in the context of bicycle tires that concluded that it is not true on rough surfaces because the thin high pressure tire bounces too much. Food for thought.

Also I don’t think the larger contact patch is the leading factor. Rather it’s the amount of rubber that is flexing and how much it id flexing and causing heat.

 

Power is the most important over mpg or grip now its not the most important otherwise i would not use an AT. I am going to stick with the AT it will never be as efficient as the stock sized all season we all know there is going to be compromise. I am just trying to figure out which would effect power more weight or width/contact patch. I think width is more into play than weight especially when we are talking under 5lbs difference, just trying to see if anyone has experience.

 

Note that in the case of tires, power and fuel economy are directly related. Tires do nothing but lose (useful) energy. They never create it.

 

Honestly, going back to 245/75R16 will make the biggest difference.

You regain gearing, its narrow, and the tire is lighter, even the cooper at3 4s is lighter than your choices.

Diameter, weight, rolling resistance, all matter.

1/2" tire clearance on a trail is important, but with a 4 banger auto the daily driving matters a lot.

I run 245s for winters on my v6 and actually look forward to putting them on over my 265 75's.

 

Are you sure? That is a 10ply E load tire.

 

Looks like it

 

Rolling resistance plays a small role in overall vehicle resistance. While measurable under controlled conditions, it can be unperceptible in real-world conditions.
https://m.tirerack.com/tires/tiretech/techpage.jsp?techid=29

That said, as far as rolling resistance is concerned, one of the easiest things you can do to decrease/maintain/control rolling resistance is maintain the vehicle manufacturer's recommend psi, or use the proper adjusted psi when switching to a different size and/or load rating. Yet another reason why the chalk test sucks.

@Nyrob
Section width doesn't necessarily correspond to tread width. A 265 can have anywhere from 7.5" to 9" tread width.
From your two choices, you might expect an almost 1.25" difference in tread width. The tread width of the 265 is 8.1", the 235 is 7.1".
The 235 is an LT with 17/32"; the 265 comes in at 13/32". All other things being equal, higher tread depth has higher rolling resistance.
IMO, the difference between the two in real-world driving would be almost, if not completely, nil.

 

Yes, the XT version, not the AT you originally posted.

 

I've had P265/75/16's on my truck and E rated LT 265/75/16's on my truck. Same size, very similar All Terrain tread, but the E rated tires were 15 lbs each heavier (38 lbs vs 53 lbs). Fuel mileage didn't change at all. The truck took a little longer to accelerate from a stop or when merging in traffic with the heavier tires. It does take more power to get them moving, but once up to speed if anything the heavier tires keep rolling easier.

I have seen trucks lose 2 mpg going to a mud tire after an All Terrain tire even though they were the same size and load rating. Rolling resistance makes a big difference.

But for what you're looking at there isn't enough difference to matter either way.

 

wut? Rolling resistance is easily perceptible and measurable both with automobile and bicycle tires. Are we perhaps using different definitions?

Rolling resistance is generally a lower cause of energy loss than air resistance because it is proportional to velocity whereas air resistance is proportional to velocity squared, but it is still a factor.

https://www.nhtsa.gov/DOT/NHTSA/NVS/Vehicle Research & Test Center (VRTC)/ca/Tires/811154.pdf

My personal experience is that I observe a 1-2 mpg difference between my 255/85/r16 e-load mud-terrains and my 265/70/r16 SL all-terrains (corrected for tire diameter). I don't think this can be attributed to the difference in tire weight as the mud-terrains have only ~80lbs of extra "equivalent mass" (mass + rotational inertia).

I do agree that small differences in tire size with all other things the same probably have a negligible effect on rolling resistance.

 

I'm saying the difference(especially in the OPs example), is insignificant enough, that differences in day-to-day real-world driving, "can be" unperceptible; not 'will be'. I try to choose my words carefully...

 

In the OPs case I tend to agree, but I don’t agree in general unless 1-2 mpg (~5-10% on my truck) is considered insignificant. I mainly bring up rolling resistance in these threads in response to common belief that tire weight, because of its added rotational inertia, is a significant contributor to overall efficiency of the truck. People often disregard other aspects of the tire.