315/70/17 vs 35x12.50x17

Barth Vader

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I’ve got the 315 BFG KO2 A/T’s. I went through the same debate and don’t regret my decision. No lift FYI, but it is a debadged Rubicon.

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z0lt3c

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For those still shopping around, Goodyear just announced a 20% rebate offer across their entire tire product family if you buy online. That means you can pickup Duratracs in 315/70/17 for about $275 each right now, which I think is a great price. You need to use code NASCAR20 at checkout to get this discount. Offer is good until 6/30 !!
 

PhantomChameleon

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When I was looking at tires, it looked like many of the 315's were a little shorter and a little wider than the 35's.

I prefer to have a taller, thinner tire (more height is a huge part of why I want different tires anyways), so I went with the 35's...the difference may not be much to really matter, but that was part of my reasoning for choosing the 35's.

I ultimately ended up with Yokohama Geolandar X-ATs and love them so far. They are load "E", so a bit stiffer than the stock tires - but its really not bad or even very noticeable unless you expect your Jeep to ride like a Cadillac...but in that case you probably bought the wrong vehicle. I also love the toughness of 10 ply tires, no flats due to the sharp rocks here in Colorado with these things!
 

Alabama Mud Machine

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There is a method to my madness and why I run 20's on everything... Yes, I like the way they look better than the "more tire, less wheel" balloon look. I like the squared-off look (personal preference). But I also have lots of experience running everything from 15's to 20's, and 265's up to 44" TSL's... So I do have some (non-scientific) personal experience data to back up my methods. :like:

People really overthink the C, D, & E tire ratings. A C-rated tire will be softer than an E-rated tire, but it will also NOT handle as well on the road. And E-rated tire has a much stiffer sidewall. And most of you are running 17" wheels. That leaves A LOT of sidewall to flex on asphalt driving. Sure, that is a good thing for offroad, but lets be honest about how much we TRULY offroad our brand new $40,000+ JT's... I know mine doesn't get wheeled yet, and won't get wheeled until my lease is up, and I have the loan in my name. Offroad, absolutely, but nothing hardcore that could cause any severe damage to the vehicle. So mine mostly stays on the road as far as driving goes, other than hunting, fishing, and working around the property. So, to me, I want better on-road handling, and superior tire tread wear. In those departments, the E-rated tire will almost always be superior to the C-rated tire. Exceptions being cheap shitty chinese or offbrand tires (or vehicular issues like poor balancing job, misalignment or camber, caster, or toe issues).

I didn't mention D-rated because it's going to be directly in between, so comparing C to D, or D to E wouldn't be very noticeable. But going from C to E is quite noticeable in many factors.

I'm running 37x13.50r20 E-rated tires... My Jeep handles great other than the factory steering slop. The Fox 2.0 TS stabilizer helped tremendously as far as steering feel and on-road manners, but it's no miracle cure, and I still have a slight dead-spot in the middle of the wheel, and a little bit of shimmy (which I have been told is flex in the stock aluminum track-bar and tie-rod. Hopefully when I swap in the Evo front springs, Evo track bar, and Evo lower control arms, it will help fix the issue by correcting the steering geometry (by adjusting the LCA's).

Just my personal thoughts having run all the different types of tires for years on everything from a Taco to a JTR, old 70's & 80's Chevy K trucks to many different model Z71's, and several Ram 2500s, and an F-250 Powerstroke.
 
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z0lt3c

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People really overthink the C, D, & E tire ratings.
My issue with going to an E tire on the Gladiator Sport is my stock tire is a 33lb SL rated tire, which is roughly equivalent to a B rated LT tire. It's a pretty huge jump from B to E, thus I think it's logical to believe the suspension is designed around the type of sidewall flex expected from a SL tire and not the stiffness of an E tire. I guess I'll let you know when I get them installed.

In addition, typical E rated tires achieve load ratings, and therefore stiffness, when run at the maximum PSI, which is typically 80. I would hazard a guess you are NOT running your tires at 80 PSI and thus your not actually riding on a fully stiffened E tire. If you are running at a more typical 35 PSI, you are at around 1/2 the tire max and have reintroduced some flex back into the tire. Where-as the C tire the max is 50 PSI and running at 35 PSI is much less a reduction.
 

Alabama Mud Machine

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My issue with going to an E tire on the Gladiator Sport is my stock tire is a 33lb SL rated tire, which is roughly equivalent to a B rated LT tire. It's a pretty huge jump from B to E, thus I think it's logical to believe the suspension is designed around the type of sidewall flex expected from a SL tire and not the stiffness of an E tire. I guess I'll let you know when I get them installed.

In addition, typical E rated tires achieve load ratings, and therefore stiffness, when run at the maximum PSI, which is typically 80. I would hazard a guess you are NOT running your tires at 80 PSI and thus your not actually riding on a fully stiffened E tire. If you are running at a more typical 35 PSI, you are at around 1/2 the tire max and have reintroduced some flex back into the tire. Where-as the C tire the max is 50 PSI and running at 35 PSI is much less a reduction.
I’m running 45 PSI in my 37x13.50 E-rated, and they’re performing nicely. :like:
 

LostWoods

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My issue with going to an E tire on the Gladiator Sport is my stock tire is a 33lb SL rated tire, which is roughly equivalent to a B rated LT tire. It's a pretty huge jump from B to E, thus I think it's logical to believe the suspension is designed around the type of sidewall flex expected from a SL tire and not the stiffness of an E tire. I guess I'll let you know when I get them installed.

In addition, typical E rated tires achieve load ratings, and therefore stiffness, when run at the maximum PSI, which is typically 80. I would hazard a guess you are NOT running your tires at 80 PSI and thus your not actually riding on a fully stiffened E tire. If you are running at a more typical 35 PSI, you are at around 1/2 the tire max and have reintroduced some flex back into the tire. Where-as the C tire the max is 50 PSI and running at 35 PSI is much less a reduction.
I generally agree going with a C or D-rated tire. E-rated tires have more tread plies which massively impact ride quality (as that's your road-tire interface) but will frequently have the same 3 plies in the sidewall as their C or D-rated counterpart.

Unfortunately, this is not the case with the KO2. Don't get me wrong, I too bought the C-rated 315's because they do what I want but with one less ply, they're going to have more roll than the E-rated version. The difference in tire pressure that you'll be running on a light truck like a Gladiator isn't going to make up for that difference all that much.
 
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Hit my local Discount tire today for a set of the C load 315 Bfg’s & pretty happy so far. Fit’s perfect on the spare wheel also & under the truck. I was hoping to have the lift on first but with any luck the Mopar lift will arrive this week. The only thing that would have been better is if I didn’t miss the $100 rebate. ;(

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DaveFrat

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Hit my local Discount tire today for a set of the C load 315 Bfg’s & pretty happy so far. Fit’s perfect on the spare wheel also & under the truck. I was hoping to have the lift on first but with any luck the Mopar lift will arrive this week. The only thing that would have been better is if I didn’t miss the $100 rebate. ;(

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Looks great
 

Maximus Meridius

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I read and read and read about all the options, loads etc . Decided on Falken Wildpeaks 315/70R/17” all terrain not mud terrains. It is the exact tire as the 35/12.5” 1/8” shorter and 1/4” wider than 35’s. Same loads and everything and $75 a tire cheaper when I got mine plus free delivery and it was the next day. The only difference is what’s blazed on the sidewalls. If you want to spend $300 more for a set of 4 to say 35/12.5/17” on the sidewall you have way more money than me. Just my opinion. They ride fine at 32psi and look and perform great.
$ 1031 to the door.
 

steelponycowboy

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Everyone will have an opinion on tires so I'll give mine for whatever it's worth.

I've gone with 35's on by a number of companies Yokohama, BFG, Goodyear, Atturo and a few others over the many years I've been building my own Jeeps.

The last time I bought Yokohamas M/T tire the tread was directional which I found to be an issue, especially if you have a flat and the spare is not in the right direction. Won't buy them again.

Won't buy Atturo's M/T tires either. 10,000 miles in I got tread separations and sidewall separations. My son had the same issue with Atturo's and he won't get them again either.

BFGs are a good tire but I found that the wear and performance didn't match the Goodyear MTR Kevlars.

I've never had a flat with the Goodyears (kevlar sidewalls) and their ride for M/T tires was exceptional and not as loud as some of the others. I got 40,000 miles off of one set with still enough tread to sell them to someone who wanted a cheap set of 35's and he probably got another 10K miles out of them. My Jeep buddies seem to have the same high opinion of the Goodyear Kevlar MTRs.

I am an avid overlander and my Jeeps see as much or more off road than they do on. I average 5K to 8K miles a year off road. Pretty much more than the average person (other than the guys I run with) I' m sure. They get another 5 to 8 of pavement. This year due to Covid, I'll end up still with 3500 miles doing the Continental Divide Trail from Canada to Mexico, 900 miles on the AZ Peace Trail Loop, 300 miles on an expanded Devils Highway trip and a few others that will still put me well above 5000 miles off road for the year.

Tire size I typically get are 35x12.50x17. If I ever go to 37's I will most likely go with a 20" rim. The advantage of the 20 in rim for me is I can go with a much bigger Baer Big Brake system than I can with 20's and I like the look of less rubber but still enough to air down and get to business. Unlike most, I now usually replace my tires at 20K to 25K miles for new ones and sell the old ones that still usually have close to half tread.
 

NateKY

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For those still shopping around, Goodyear just announced a 20% rebate offer across their entire tire product family if you buy online. That means you can pickup Duratracs in 315/70/17 for about $275 each right now, which I think is a great price. You need to use code NASCAR20 at checkout to get this discount. Offer is good until 6/30 !!
That is a good price for Duratracs. However if you like the Duratracs, check out the Kanati Trail Hogs made by Greenball.
 

                           
























































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