Tire upgrades

2015JK518 said:

Currently running procomp mt 305/66 17 and want to upgrade to BFG ko2. Can someone tell me what’s the difference between 315/70’s and 35x12.50’s. Thanks! Also if the 305s don’t currently rub on stock suspension, would either of these 35s?

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Your 315 is a 34.36" tall tire. While your 35 is an actual 35" tall tire. The width between the 2 different sizes is only an 1/8th of an inch. Someone else will have to chime in on 35's fitting stock suspension though.

2015JK518 said:

Thanks! I was always under the impression the first set of numbers resembled the tire width, not the height.

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You're welcome!

Use this site to really get into the weeds of tire sizes.

The first number is the width in millimeters, the 2nd is the aspect ratio of the sidewall, or percentage of tread width that is the sidewall. Last one is rim size in inches. Dang 'mericans that can't do metric . So 66% of 305mm (12") is 201.3mm or 7.9". So your total advertised tire height would be (7.9 x2) + 17 - 32.85". I say "advertised" because you would actually have to check the manufacturers website to see what the measured height is.

Also no two brands of tires are the same. I install tires in my shop. (Some. Not much. I despise balancing tires.) Ive seen worn out 285/70 setting beside brand new 295/75 and the worn smaller ones were taller. Ive also taken one brand off a vehicle and put another brand on(same size) and have massive rubbing.

My new cooper stt are a good deal taller than my km2 were even though they are supposed to be the same size. They rub slightly on my sway bar where the km2 never hit. So be wary of the differences

The km2 are probably my favorite all around mud terrain. I've run most, if not all of them.

2015JK518 said:

want to upgrade to BFG ko2.

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I upgraded my Toyo MTs (35x12.5) to BFG KO2s almost 5000 miles ago- getting close to rotation time.
Could not be happier. Of course, going from the heavy and stiff sidewalls of the MT to an all-terrain is one thing, but the noise reduction, ride quality and grip on the road is so much better.

I've ran the bfg AT tires but got just as sorry mileage as I did the km2. So I just ran the mt. I change my tires at half tread usually, in mud and snow they start to suck by then. I can usually sell them for half what I paid too. My jeep has 54k miles and is on its 5th set. Just installed the stt coopers. So far I'm not overly impressed. The km2 went better in the trails. Haven't had snow or mud yet though so my opinion may change.

Other than some UHP tires ive ran, and a set of super swampers, the BFG was the most disappointing on mileage of any ive ran. I had them on a 79 Ranger. It has coopers on it today. My brother in law had a set on his hemi sport and got pretty sorry mileage too. They definitely rode better and made less noise than the km2.

I think mileage is a very overrated measurable across the board. I'm 65 and owned plenty of vehicles in my lifetime. I've never made a decision on what vehicle to buy based on gas mileage. It doesn't matter to me, I still drive and I still have to go places. The comfort, use, aesthetics and are far more important to me. When you're 6'6" and hovering close to 300lbs, there aren't many mileage conscious vehicles out there that I drive comfortably. Consequently, a couple Tahoes, an Expedition and another Jeep were in my stables at different times since 1995.
If I was concerned about mileage, I wouldn't own a Jeep. There are a lot more reasons than gas mileage not to own a Jeep for the vast majority of car owners, so for those of us who do own them, mileage is just another one of those things to complain about.
None of the other vehicles I've owned in the past 25 years were all that on gas mileage either, so....

And when it comes to tires and gas mileage, there have been plenty of threads here that talk about airing down MTs to get a better ride. When you have a 34psi MT tire and air it down below 30 somewhere to improve the ride quality, you're going to sacrifice mileage.

Anybodyhome said:

I think mileage is a very overrated measurable across the board. I'm 65 and owned plenty of vehicles in my lifetime. I've never made a decision on what vehicle to buy based on gas mileage. It doesn't matter to me, I still drive and I still have to go places. The comfort, use, aesthetics and are far more important to me. When you're 6'6" and hovering close to 300lbs, there aren't many mileage conscious vehicles out there that I drive comfortably. Consequently, a couple Tahoes, an Expedition and another Jeep were in my stables at different times since 1995.
If I was concerned about mileage, I wouldn't own a Jeep. There are a lot more reasons than gas mileage not to own a Jeep for the vast majority of car owners, so for those of us who do own them, mileage is just another one of those things to complain about.
None of the other vehicles I've owned in the past 25 years were all that on gas mileage either, so....

And when it comes to tires and gas mileage, there have been plenty of threads here that talk about airing down MTs to get a better ride. When you have a 34psi MT tire and air it down below 30 somewhere to improve the ride quality, you're going to sacrifice mileage.

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I meant mileage out of the tires. Not fuel mileage. Ive never concerned myself with fuel mileage. And the vehicles that I've had that probably should have got decent fuel mileage weren't impressive. Currently I have 10 vehicles either tagged or could be. My mach one gets my best mileage. Lol. I can stretch it to 27ish highway . Closer 17 around home . My 2021 5.0 f150 gets around 23 highway and 19 around home. My 79 big block gets around 8. Our v10 gets around 11. My 66 big block gets around 16 but it's 3 on the tree and geared stupid high. Will break 100 in second. Our highlander gets 18 locally. Might hit 24 on the highway. But if I'm driving that one, I have 5 passengers and a luggage rack full. Easily the most comfortable vehicle I've owned and that's including a benz, 2 Denali, and my new f150). Best reliability too. I'm a domestic driver though. Lol. No imports for me. My JK rubicon 6 speed with 285/70-17 got close to 10 going to the coast running 80. I can get closer to 18 locally. Took 4 fuel stops lol. I had fun wheeling on the beach though

We have owned some cars, such as a 3.5 liter rt avenger and a couple subaru that we thought might get us better mileage but the avenger got around 24 but required oil and some parts every full up lol. The subaru never got over 24 highway. Terrible for a naturally aspirated 5 speed car that weighed well under 3k. Many years ago I went to buy a 93 5.0 mustang 5 speed. Well it turned out to be a 2.3 liter 5 speed but was in great shape and I got it for 500 bucks. It got 38 mpg too. My personal best by a mile. Next would be my first car, an 86 mustang lx 4 speed. Carbureted car. It got around 32. Both were unbelievably slow. I still have every car but the Avenger

But I was referring to the mileage we get out of tires. The BFG AT tires were the most disappointing on my truck and my brother in laws hemi. My 21 came with some awful Goodyear territory AT tires. The Cooper stt I have now are my 5th set in 54k miles but again, I take them off with half tread and sell them. They don't go good by then anyway. I think the km2 is still my favorite and I have run everything as well as install tires at my shop. They are a good balance of drivable and offroad ability. I also never lost a bead with one. I run 8 lbs for months on end with them. Some, like the swampers, went incredible but turn any vehicle into a death trap. Bad mileage too (as in bald In 10k). And some like procomp mt, and maxis bighorn/buckshot nearly always come back after I put them on a nice newer truck. People hate the ride and handling. Not so much in jeeps and the like. Ive never had anyone complain about the km2, the mtz, and a few others. I put a set of Kelly mt on a duramax the other day. He said they weren't awful.... lol.

I get ya, but, by the same token, varying the air pressure to achieve a better ride will also effect the mileage performance of the tires. I got 60k out of my Toyo MTs, only because I ran them on the road a little above 30psi. If I aired them down to 26 or so to get a better ride, I'd get nowhere close to 60k.