Tire size vs. weight affecting performance

[kottster]

Hi everyone, first of all, excuse me asking this question if this has been answered elsewhere. I’ve been perusing these forums for almost a year, and I’ve found plenty of useful information, but nothing specific to this question I now have.

I just got a 2017 4Runner and want to go with bigger tires, but know my power and MPGs will take a hit the bigger I go (I ran 33s on my ’97 4Runner and ended up having to change my gears because I lost so much power). I ran BFG TA KOs and am inclined to go with them again. I’m deciding between running 275s and 285s. I see the BFGs in either of those sizes is heavier than other all-terrain tires (probably due to them being E class vs. some others available in C).

My question is which is worse for my mileage and power - a larger diameter/circumference, or a heavier tire?

How would a 45lb Nitto 285 compare with a 55lb BFG 275? I imagine both factors have an adverse effect on mileage and power (larger circumference tires are more difficult to turn, but so, too, are heavier ones), but which is worse? I’d like to go with 285s, but not if that means I’d need to re-gear or deal with significantly degraded performance. But if I can get away with a similar performance degradation with a lighter 285 as a heavier 275, I may do that. Can anyone here help with this?

 

[TRUSTYAXE]

[MENTION=64701]kottster[/MENTION]
Get some NRG load C 285’s and never look back.
:lookout:

 

[LandCruiser]

I have FJ cruiser steel wheels and Firestone destination MTs in 285, you can definitely feel the weight of those things, and fuel economy is 13 to 14.

 

[83Mule]

If you don't Off-Road much get the light 285's.......get an E rated 275 if you do.

 

[DesertCanyons]

285 vs 275 tire size

Your sig' doesn't reveal where you live. That might give us a clue as to the kind of terrain you're driving. How do you plan to use these larger tires?
If you're only going to drive it on pavement or dirt roads then the stock tires are the most efficient for the 4Runner.
Are you installing a lift to accommodate the larger tires?
The hit in mileage and acceleration is due to rotational inertia. There's a physics formula that could tell you which has more inertia. That inertia determines the resistance to change in speed, aka acceleration. Depends on where the weight is located too. Is it in the tread or the sidewall? An E rated will have thicker sidewalls. A C rated AT tire might have more of the total weight in the tread. An aggressive mud tire will have thick tread. A road tire will have a more even distribution of weight. It's not likely you can find this weight distribution info or know and calculate the formula unless you're a physicist or mechanical engineer. I'd have to look it up and I'm a Civil Engineer.

 

[Jetboy]

I've taken P285s around basically every Moab trail that a 5th gen on 285's can run. I've run the Rubicon - on P rated 285s. I've done blackbear/Imogene pass on p rated pure street tires on 20" wheels. I'm not sure where you're going - but if it's harder than those trails E rated tires might make sense. If you're going to race in the Baja - probably go E rated. Otherwise there's not a great reason to have all the side effects of tires made for an F350 on your 4runner. And don't buy Toyo AT2's - I have them and it's been a less than great tire in terms of street use for an AT.

Now that I run two sets of wheels/tires, I'd probably consider an E rated 285 for my offroad set, but mostly because all the MT tires are usually only offered in an E. I'd prefer a C rated if it were available, but I can't fit 35's, and in a 285 there's just not much aggressive options that aren't E rated.

 

[Decipher]

We need more info on your off roading needs and terrain for sure.

If you’re looking at purely aesthetics with no need for off road performance, then get the lighter tire. Less rotational mass means less ill effects.

If you’re like me where you only do moderate off roading and none of it is on sharp rocks, you could even do what I did and (gulp) go P rated if possible. I have great MPG (18 average city) and have an extremely capable tire for my needs with good road manners.


Sent from my iPhone using Tapatalk

 

[1engineer]

Mass trumps circumference. Accelerating the mass from rest is what affects your mpg, especially around town. Larger diameter affects gearing which affects power which affects mpg.

 

[comtn4x4]

For me it seemed the weight made more difference in the power of the truck. When I went from 285/70 at 54 lbs to 285/75 at 65 lbs the truck really lost a lot of power and wandered through the gears badly. I ended up re gearing because of it. (Although keep in mind I'm in Colorado)
I agree with what was said above, go the lowest rating tire you can. The truck simply isn't heavy enough to warrant more unless you are really going through some aggressive terrain. And as far as rating and weight goes... with Nitto Ridge Grappler for example, the same size tire in C and E the C actually weighs more than the E, but the C is more forgiving or more pliable and rated for less weight.

 

[JSparky]

I think this is an interesting question. I know it can be estimated mathematically but I wouldn't mind seeing some real world numbers. One of the jeep magazines compiled some test data on this very questions but I couldn't get the whole article to load for some reason.

Practically speaking a ton of us run 285/70/17's with the 4.0 and stock gears without a problem, Tacoma's and FJ Cruisers included. Sprint Booster's remap the throttle which can help keep you in a higher rpm range if you desire, lots online about that.

Lastly, if you find a good tire shop they'll usually let you swap tires within a specific amount of miles if you're not happy with your purchase. I know two shops near me that will happily swap tires (America's Tire and Wheel Works), I know because I've had to do it!

 

[S54MCoupe]

I always wanted to run Hutchinson beadlocks. They're just so damn heavy I can't bring myself to do it.

 

[Oey12]

In regards to your main question OP...based on my limited but detailed experience I found that the larger diameter tire affected mpg's and power much more than tire weight. After calculating every tank of gas, after 20k on my P265/65r17 Nitto Terra Grapplers (41.8 pounds as per scale) I averaged 20.8 mpg. Now after running my Michelin M/S2 P265/70R17 (40.7 pounds) for 20k I averaged 19.7 mpg (this includes the 3.4 difference in size calculation). My commute stayed the same and I am a highly conservative driver, meaning I drive slow. I completely understand that they tires that I am comparing are in a different league than the tires you are looking at but I hope you can take something from it. But the smaller heavy AT tire was better than the larger diameter highway super low resistance lighter tire.

 

[kottster]

Thanks for all the replies so quicky, guys. So I will be doing minimal off-roading, I want the bigger tires more for the looks and to differentiate myself from stock. I live in northern California and head to Tahoe a lot in the winter. Might get into 4 wheeling now that I have a 4Runner again but that still is not what I'm primarily solving for with this tire decision. I was actually set on going with 275s for a while instead of 285s just out of fear of going too big (the mistake I made with my '97), until I started hearing people talk about how unnecessary an E rated tire is - it certainly will be for me. At this point the options I'm contemplating are (to go along with a 2.5-3" lift):
1. 275 C Cooper AT3 @51lbs (also saves me some $$ over the BFGs)
2. 275 E BFGs @ 55lbs (and say to heck with the extra weight and go with what I think is the most aggressive looking tire out there)
3. 285 C Nitro Terra Grapplers @45lbs - or now that it was suggested:
4. 285 P Cooper AT3 @44lbs

 

[1engineer]

Thanks for all the replies so quicky, guys. So I will be doing minimal off-roading, I want the bigger tires more for the looks and to differentiate myself from stock. I live in northern California and head to Tahoe a lot in the winter. Might get into 4 wheeling now that I have a 4Runner again but that still is not what I'm primarily solving for with this tire decision. I was actually set on going with 275s for a while instead of 285s just out of fear of going too big (the mistake I made with my '97), until I started hearing people talk about how unnecessary an E rated tire is - it certainly will be for me. At this point the options I'm contemplating are (to go along with a 2.5-3" lift):
1. 275 C Cooper AT3 @51lbs (also saves me some $$ over the BFGs)
2. 275 E BFGs @ 55lbs (and say to heck with the extra weight and go with what I think is the most aggressive looking tire out there)
3. 285 C Nitro Terra Grapplers @45lbs - or now that it was suggested:
4. 285 P Cooper AT3 @44lbs

Your choice man. Just remember unsprung mass is a buzzkill especially around town. Math don't lie haha.

 

[JSparky]

If you're going for looks I wouldn't even consider a 32, at that lift height 33's are proportional if not on the smaller side.

 

[perf0rmance]

My buddy in his 3rd gen slightly regrets getting Load E rated BFGs for MPG purposes His T4R is his DD but he doesn't drive everyday lol. Being in the Bay Area, there aren't very many difficult trails that are nearby so if it's your daily driver, I'd suggest getting a lighter tire.

Switching from a 265/70/17 to a 285/70/17 will roughly net a 3% drop of revs per mile - obviously this is due to the larger circumference of the tires. How much does that affect MPG??? I'm not sure, but the difference of weight in the tires will probably be between 10%-15%.... something to think about.

 

[kottster]

If you're going for looks I wouldn't even consider a 32, at that lift height 33's are proportional if not on the smaller side.

I will definitely try to pick the right height lift to complement the tire I go with. Right now I'm leaning towards going with OME 2884s up front for 2.5-3" of lift and SAW 1.5" coils in the rear. I'm pretty sure that will accommodate either 275s or 285s

 

[1jzgte]

Thanks for all the replies so quicky, guys. So I will be doing minimal off-roading, I want the bigger tires more for the looks and to differentiate myself from stock. I live in northern California and head to Tahoe a lot in the winter. Might get into 4 wheeling now that I have a 4Runner again but that still is not what I'm primarily solving for with this tire decision. I was actually set on going with 275s for a while instead of 285s just out of fear of going too big (the mistake I made with my '97), until I started hearing people talk about how unnecessary an E rated tire is - it certainly will be for me. At this point the options I'm contemplating are (to go along with a 2.5-3" lift):
1. 275 C Cooper AT3 @51lbs (also saves me some $$ over the BFGs)
2. 275 E BFGs @ 55lbs (and say to heck with the extra weight and go with what I think is the most aggressive looking tire out there)
3. 285 C Nitro Terra Grapplers @45lbs - or now that it was suggested:
4. 285 P Cooper AT3 @44lbs

https://www.fnwheels.com/new-products/bfd/

These are probably the largest and lightest combination you can find out there. I'd go with the biggest diameter rim since alloy tends to weigh less than rubber. More weight on the outter circumference on your wheel will take more energy to move than weight closer to the hub.

 

[Geezer81]

I have FJ cruiser steel wheels and Firestone destination MTs in 285, you can definitely feel the weight of those things, and fuel economy is 13 to 14.

I have the same steels w/ E rated Cooper STT's 265/70/17 and can feel the loss of power. MPG took a dramatic hit too.

 

[JSparky]

https://www.fnwheels.com/new-products/bfd/

These are probably the largest and lightest combination you can find out there. I'd go with the biggest diameter rim since alloy tends to weigh less than rubber. More weight on the outter circumference on your wheel will take more energy to move than weight closer to the hub.

If I remember correctly the FN's are actually a lower cost replica of a Volk. The FN is cast while the Volk is forged. You'd have to check but I believe the Volk was lighter and stronger, but also 4x as expensive.

I had the FN Countersteer Type-X in the past and thought they were great, my friend runs them now with no problems.. I second this recommendation if you want a lightweight affordable priced wheel.