Should I go with 275/70/18 or 285/75/18?

I’m trying to decide on the size for my new Toyo open country AT3s. I have a 2008 with a ARB bumper, so I don’t think rubbing will be an issue. I only off road a couple times a year, and don’t want to lose a lot of on road performance. The bigger tires are 13 pounds heavier. Do you think it’ll have a large impact on performance, mpg going with the larger tires? Will it hurt/ stress the truck?
If anyone has experience with both sizes I’d appreciate hearing it. Thanks.

 

You're really on 2 different ends of the comparison spectrum...

275/70s are just a hair over 33s", and the 285/75s are a hair under a skinny 35"...

I don't think weight is going to make that much of a difference between the 2 tires for you, and as a reference point take a look at the weight differences between 3 available OE tundra wheels:

OE steel wheel that comes on the Tundra weighs 39 lbs.
OE SR5 alloy wheel weighs 32 lbs.
OE BBS-FORGED alloy wheel that comes on the newer PROs weighs 27 lbs.

In other words there's a 12lb difference per wheel type being offered on these rigs. So, I think if weight alone was an issue, we'd be seeing premature wear on the bearings, etc. on any truck running the OE steelies, but this isn't the case. I think proper offset has far more bearing on premature wear of bearings and other components such as CV axles, etc...

I really think this comes down to looks as you stated you're not looking for an off-road improvement that a larger tire w/more sidewall provides. Do you like the appearance of what would basically be a stock height tire and the way it fills the wheel wells, or would you prefer to have a more 'full' look in the wheel wells that the 285/75s will provide....

MPG... You'll probably lose 1mpg +/- with the larger tire, and keep in mind your speedometer will be off about 5mph (at FWY speeds) w/the larger tire as well.

There are plenty of threads here w/guys running 285s that bought em, love em, and haven't looked back. When my OE tires are ready for replacement on my '21 Pro, I'll be putting a 285/75 on it w/o thinking twice about it.

I'd spend some time in the tire size threads here and take a look at some of the photos of the rigs running both sizes and go from there...

Here is a member's truck with 275/65s (he does have the OE Pro Suspension, so front end is leveled and up a bit from OE)



Here's his truck with 285/75s...


Another member's stock Pro with 275/70s Wildpeak AT4s...

 

I went from 275/70r18 Coopers to the toyo at3 in a 35x12.50/17 and I did notice it's slower off the line and struggles more with towing in the mountains. The mpgs stayed about the same, around town/flatland shouldn't be a problem. I definitely prefer the look of taller sidewalls on my truck.

 

I’m running Wildpeak AT4 in 285/75R18 with CBI bumper. My mileage, surprisingly, hasn’t changed from stock 275/65. I love them, and my only wish is that I had gone bigger. Biggest drawback for me is it’s much harder to rotate or change tires due to size/weight. It’s a bitch for me, but can do it. The 275/70 is only 1” bigger diameter than stock. Id definitely go big, especially with your bumper.

 

I have found Mpg and acceleration is identical 275/70/18 and my previous 35x12. Might as well get bigger if your gonna take the performance hit anyways.
The only difference is 6th gear is usable on flat ground on the freeway with 275/70’s. 35x12’s youll never use 6th gear unless coasting down a hill

 

Currently running 275/70r18 with the RCI bumper and skid plate. Getting about 14mpg average. tires are the General Grabber ATx with Method 705.

 

285/75/18 fit these trucks perfect.

 

Yokohama Geolanders? How do they handle wet roads and rocky trails?

 

I like my 285/75 Kenda RTs. It’s an aggressive tire, but was still managing 15.3 mpg today on the highway at 72mph and we have hilly highways here in my area. Mine is SC’d so it’s probably not comparable there, but it holds 6th with a locked TC on the highway even up the hills despite the tire size and weight on stock gears. If you’re going to look at other trucks with bigger tires and have longing eyes, do the 285/75s. If you don’t care about all that, maybe it’s worth the other benefits to have the 275/70. More sidewall means a better ride too don’t forget.

 

will the 285/75r18 spare fit underneath? Looks like it might be tight or some cutting fo brackets might have to be done. I have plenty of room with the 275.

 

they were decent for about 20k on wet roads, then became a little slicker as the mileage increased.

Yes. Just cut the tabs off and it will fit. I have one mounted under there.

 

https://www.tundras.com/threads/true-35%E2%80%9D-spare-does-fit.146517/#post-3675689

I’ve got Coachbuilder shackles, and it’s very tight (could reverse the shackle bolts)

 

I can hold lockup in 6th at 62-65mph on stock gearing with 285/75s. No blower (yet?), but using T/H mode. Any faster and I’m hunting on hills.

My problem is, I just bought some rock warriors, so I need a similar sized tire for a 17” wheel.

 

good to know, need to upgrade my rear leafs also. Will flip the shackle bolts when I do. Thank you.

 

315/70 or 305/70 are probably the move. I’ve had both of them over the years on 0 offset 17x8.5s.

 

Probably a bit heavier than the 285/75/18s.

If I’m going heavier, might as well do 37s

Edit:
Duratracs in 315/70/17 are D load. 62 lb. Slightly smaller diameter than 285/75/18…
Hmmm….

 

You will be saving weight anyway with the rock warrior wheels only weighing 24ish lbs each IIRC. I had Goodyear territory MTs in 315/70r17 Load C, they only weigh 54 lbs. and can be found quite cheap. Those are small for a 315/70 however. I have also had duratracs on my prior 2010 tundra in 315/70. Phew… gotta stop looking at old pics of those Method 314s. They really do it for me…must resist purchasing more wheels and tires.

 

Did you trim any on the wheel wells? I have Eibach pro 2s and looking to add the coachbuilder +3 shackles and 315/70/17s. Currently on 295/60/20, but a worried about the almost full 1" increase in width.

 

My front fender liners have been messed with and pushed forward before. The 315/70s I had were small, not sure which tires you’re going with but that and wheel offset is a big variable.

 

My 2010 SR5 has 'S' Mode(Sequential Shift) so I can decide which gear is correct for load, speed and road conditions. My transmission never "hunts" for the right gear.

 

It does.

Go up a long grade at 70mph.

The bigger your tires on stock gearing or the heavier your truck, the less you will see 6th gear at highway speeds even if you use Sequential Shift. Monitoring with the Fusion OBD app, I can barely keep lockup in 6th gear in the hills of Tennessee with my speed in the low 60s.

At 75+? No way. I’m on stock gearing, no boost, skinny 35s.

Sequential shift only locks out gears higher than what you have it set to; it cannot make your truck stay in 6th gear.

S6 behaves the same as D. It’ll unlock the TC, downshift to maintain speed, etc.