real world tire weight on mileage impact

[mook21]

I had the opportunity to do as close to an apples to apples real world comparison between tires in E load rating and P load rating. Here's the back story, I have a lifted 2012 TE and was running Firestone Destination 275 / 70/ 17 C load tires for several years. Last fall, blew sidewall on one and went to a used set of 285's in a mix of E and P load (caused interesting problems mixing) and liked the beefier look. About 1 month ago, purchased Cooper ATP's from Discount Tire Direct in LT285/70/17 load E. Offroad was phenomenal, on roan, optimum inflation was 40psi (using chalk method). Firestones were dead silent on road, the ATP's are a bit noisy comparatively and made the 4Runner ride like a wagon… very rough. Had a trip down to NC where Discount Tire has stores. After talking to a product manager with Cooper and getting his feedback (AT3 is designed to be the premium Cooper AT tire designed to deaden road noise but provide excellent snow and off road traction, ATP designed for Discount Tire to be as good off road, but gives up some of the features in snow and mud shedding and not as quiet. Same compound and carcass.), decided to go with AT3 in P metric (please no lectures on P vs. E for 4Runner, will get steelies with MT's for heavy off road driving). Here are the facts:
Cooper ATP LT285/70/17
weight: 55lb per tire Tread depth 17mm MPG: 15.3
Cooper AT3 P285/70/17
weight: 45lb. per tire Tread depth 14mm MPG 16.8

This was measured 300 miles each way. On this trip, I had 2 whitewater kayaks on the extended 60" roof racks, so that is why my mileage was so low. Boats were on roof rack on both trip down and back, 300 miles each way.

So looks like the added tire weight accounted for 1.5 MPG

Also, the AT3 tires are much more quiet, almost as silent as the Firestone Destinations and ride extremely smooth!

 

[thebwlife]

Can you guess when I got my lift and 285's? This is 50k miles worth of data.

 

[proquip]

Cooper ATP LT285/70/17
weight: 55lb per tire Tread depth 17mm MPG: 15.3
Cooper AT3 P285/70/17
weight: 45lb. per tire Tread depth 14mm MPG 16.8

Also, the AT3 tires are much more quiet, almost as silent as the Firestone Destinations and ride extremely smooth!

[MENTION=74912]mook21[/MENTION], thank you for sharing your experience. Besides the mpg improvement, did you notice a difference in overall acceleration or stopping? When I switched from a set of P285 Toyo A/Ts to LT285 Mickey Thompson ATZs (very similar weight difference to your experience -- 44lbs vs. 55lbs, respectively), I noticed that I'd have to get on the gas a bit more to accelerate, and the transmission now hunts a bit more for the right gear when cruising at 45-50mph (e.g. if I reach a slight incline along the road, the transmission now downshifts where it didn't have to before the tire switch).

The only other point worth bringing up is that tread pattern, and related rolling resistance, has a lot to do with mpgs as well. The Cooper ATP pattern does seem a bit more aggressive (more void space) than the AT3s, and therefore I would expect the ATPs mileage to be a bit worse beyond the impact of the additional weight between the P and LT rated tires.

As for the new tires, let's see them!

 

[proquip]

[MENTION=74912]

The only other point worth bringing up is that tread pattern, and related rolling resistance, has a lot to do with mpgs as well. The Cooper ATP pattern does seem a bit more aggressive (more void space) than the AT3s, and therefore I would expect the ATPs mileage to be a bit worse beyond the impact of the additional weight between the P and LT rated tires.

On second look, the tire pattern between the two tires looks very similar.

http://www.discounttiredirect.com/product/tires/t_20110624.copvl9.xl.jpg

http://www.discounttiredirect.com/product/tires/t_20111101.copvl0.xl.jpg

 

[1engineer]

I have presented this several times (as calculations) to people. They didn't believe me.

 

[flatspin]

This is interesting.. I am wondering though what the wind speed and direction was. I get at least 1mpg difference between tail wind and head wind on the road. I imagine with the kayaks up top, it would be an difference even if the wind wasn't that high.

 

[bimrunner]

I have presented this several times (as calculations) to people. They didn't believe me.

Using your vector analysis again? :headshake:

 

[Mooney]

I have presented this several times (as calculations) to people. They didn't believe me.

Or didn't want to believe.

 

[1engineer]

Or didn't want to believe.

Yep. Nobody likes the truth, especially when it conflicts with their skewed sense of reality.

 

[thebwlife]

Yep. Nobody likes the truth, especially when it conflicts with their skewed sense of reality.

I like the truth in my skewed reality.

 

[mook21]

Wind speed, temp and other variables on the drive

Wind was very calm both days, I really feel it with boats stacked on the rood rack on their sides with stackers when there is any wind at all. Temps both days were in mid 60's. Arguably a steeper uphill run on the way back with AT3's than down (have to climb I-77 at the Va border) while on the way down it is a very gradual rise.

For the acceleration and downshifting question, I definitely notice a difference, it feels peppier. Driving today with no boats on the top, but still with the 60" Yakima racks, got 17.9 mpg on a 40 mile all highway 75mph trip. Its amazing that I can take off my cross bars (only round Yakima cross bars, but 60" long) and pick up .5 mpg.

 

[bimrunner]

Yep. Nobody likes the truth, especially when it conflicts with their skewed sense of reality.

I didn't do the math yet... But the biggest reason I did all my mods was for MPG and performance on the track.

 

[1engineer]

I didn't do the math yet... But the biggest reason I did all my mods was for MPG and performance on the track.

My magic 8 ball says yes. I do understand the confusion with new guys though. They see all these cool 4Runners and want theirs to look or perform like yours let's say. What they don't understand is simple physics.

 

[Jhalko]

My magic 8 ball says yes. I do understand the confusion with new guys though. They see all these cool 4Runners and want theirs to look or perform like yours let's say. What they don't understand is simple physics.

I don't need to understand physics to get it, take a mountain bike out with a lightweight tire up a climb then swap it out with a heavy wire bead tire and go ride up the same hill and try to tell me it isn't harder to ride up. Change the width and you'll feel it even more. Common sense

 

[thebwlife]

I don't need to understand physics to get it, take a mountain bike out with a lightweight tire up a climb then swap it out with a heavy wire bead tire and go ride up the same hill and try to tell me it isn't harder to ride up. Change the width and you'll feel it even more. Common sense

FYI 1E is an avid rider. I bet he even owns tight shorts. Maybe a helmet too.

 

[bimrunner]

FYI 1E is an avid rider. I bet he even owns tight shorts. Maybe a helmet too.

Unless he is on a "performance ride." Then, if skinny slick tires are most efficient... that means...does he really wear a compression mankini? :barf:

 

[Rubberdown]

I like the truth in my skewed reality.

Funny, I don't like any truth in my skewed reality. That just complicates things.

 

[1engineer]

Unless he is on a "performance ride." Then, if skinny slick tires are most efficient... that means...does he really wear a compression mankini? :barf:

I could just about say that I logged more miles on single track trails on my mountain bike this season (around 1,200 miles) than 99% of 5th gen 4Runners logged on trails. :
Yes, I wear bike shorts. Yes, I wear cargo shorts over them. I'm 52 years old! Yes, I wear bright colored shirts because that's the only way people would find me if I go over the side of the mountain...

Yes I own several helmets. One got cracked on a rock, one got cracked on a root, one got left on the bike on the back of the 4Runner in NC and lo and behold, it was not there when I rolled into WV.

 

[Antman]

Yep. Nobody likes the truth, especially when it conflicts with their skewed sense of reality.

LIAR!!!!!!!:becky:

 

[Jhalko]

FYI 1E is an avid rider. I bet he even owns tight shorts. Maybe a helmet too.

Yeah I'm aware, I have a garage full of bikes myself. Now if [MENTION=66316]1engineer[/MENTION] tried to use that analogy he still wouldn't be able to do it without talking physics, something about rotational weight and mass and all that gobledy gook he rants on about.

I don't even want to think about the spandex part...