My thick skull 37 vs 35

[AmericanPatriot100]

6th gear you say! Never heard of her!!

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[Wabujitsu]

My 37" KO2s were about 35.5. Noticeably smaller than my 37" Coopers at 36.5. With the KO2s my Jeep did not feel sluggish at all with the 4.88s. My gas mileage was much better and I never had issues with the tires rubbing on the fender liners.

In other words, your “37 inch” KO2s are REALLY 36” tires https://bobistheoilguy.com/forums/threads/review-of-bf-goodrich-ko2-a-t-tires-37x12-5x17.364444/

Why do tire companies insist on misrepresenting their true tire sizes?

 

[azwjowner]

In other words, your “37 inch” KO2s are REALLY 36” tires https://bobistheoilguy.com/forums/threads/review-of-bf-goodrich-ko2-a-t-tires-37x12-5x17.364444/

Why do tire companies insist on misrepresenting their true tire sizes?

They don’t. Don’t you think there’s a reason there has never been a class action or a consumer fraud case by any state attorney general?

I have no doubt that the BFG measures 36.5“ (the specified diameter) when measured correctly:

https://www.law.cornell.edu/cfr/text/49/571.139

S6.1.1 Test conditions and procedures.

S6.1.1.1 Tire Preparation.

S6.1.1.1.1 Mount the tire on the measuring rim specified by the tire manufacturer or in one of the publications listed in S4.1.1

S6.1.1.1.2 For passenger car tires, inflate to the pressure specified in the following table:

Standard	Reinforced
Inflation pressure (kPa)
180	220

S6.1.1.1.3 In the case of a LT tire, inflate it to the pressure at maximum load as labeled on sidewall.

S6.1.1.1.4 Condition the assembly at an ambient room temperature of 20 °C to 30 °C for not less than 24 hours.

S6.1.1.1.5 Readjust the tire pressure to that specified in S6.1.1.1.2.

S6.1.1.2 Test procedure.

S6.1.1.2.1 Measure the section width and overall width by caliper at six points approximately equally spaced around the circumference of the tire, avoiding measurement of the additional thickness of the special protective ribs or bands. The average of the measurements so obtained are taken as the section width and overall width, respectively.

S6.1.1.2.2 Determine the outer diameter by measuring the maximum circumference of the tire and dividing the figure so obtained by Pi (3.14).

 

[jadmt]

I was thinking of the ko2’s those are the ones that are about 68lbs. How small do they run? Wanna co-sign my dumb idea!?!?! lol

you could also look at some 35's that run bigger...my Mickey Thompson 35's run on the larger size of many 35's as do Toyo MT's. Nitto mud grapplers in 35's look as big as some 37's.....same with some interco Irok 35's.

 

[Doodles Dad]

Having a diesel helps that a lot.

my first post and I'm using voice to text so bear with me. I have a 21 Rubicon Wrangler. I had 35s (K03's)on and bumped up to 37 (Toyo) with new wheels, the combo weighs 100 pounds apiece. My jeep has 3.73s and is diesel with 3 inch lift. My jeep is a daily driver, but I do have 16 BOHs and have done a fair amount of rock crawling. There is some loss of acceleration, but I really noticed no loss of crawling power over rock gardens and steps. In fact, I've just had the front differential replaced since it bent the axle housing and sheared left front D44 Axle. there was still that much torque available with tires, gears, and motor. I had no trouble earning 10 of those badges in Moab last year on the KO3 35s. The backend was dragging in several places and tore my OEM bumper and mash my tail pipe. I was going to replace the bumper anyways and dead with something. No I'm out clear everything. Cutting that stainless steel tail pipe with a hacksaw laying out on the rocks isn't near as fun as it sounds.

as a daily driver also,the ride noise with the larger tires is noticeable and obnoxious for me. I don't think the juice has been worth the squeeze moving to 37 and would not do it again most likely. The bigger the running gear the farther away you are from help when it breaks.

 

[KHR Racing]

Seriously!!!!!!!!!! to me it’s common sense to change your gears and not be a cheap shit. Every person that I know and on this website that has changed gears said “”””I wish I would’ve done this earlier””””. You get so much zest back into your motor and trans after changing gears. I have NEVER heard one person say that “””” well that was a waste of money”””” or I shouldn’t have changed gears, that simply has not been said after somebody changes gears. You know you want 37’s…..

 

[grimmjeeper]

Seriously!!!!!!!!!! to me it’s common sense to change your gears and not be a cheap shit. Every person that I know and on this website that has changed gears said “”””I wish I would’ve done this earlier””””. You get so much zest back into your motor and trans after changing gears. I have NEVER heard one person say that “””” well that was a waste of money”””” or I shouldn’t have changed gears, that simply has not been said after somebody changes gears. You know you want 37’s…..

I've seen a few "I went too far" posts, because the shop they chose gave them bad advice. But yeah, almost nobody regrets a regear.

 

[SadRobot]

In other words, your “37 inch” KO2s are REALLY 36” tires https://bobistheoilguy.com/forums/threads/review-of-bf-goodrich-ko2-a-t-tires-37x12-5x17.364444/

Why do tire companies insist on misrepresenting their true tire sizes?

True. But in their defense I did know this before purchasing them. I went with KO2s again because I was worried a full 37" would give me too much height to fit into my garage.

I did not have them very long though. Maybe a few months before I switched to the Cooper STT Pros. I decided to risk not fitting in the garage to get better offroad performance.

 

[Wabujitsu]

They don’t. Don’t you think there’s a reason there has never been a class action or a consumer fraud case by any state attorney general?

I have no doubt that the BFG measures 36.5“ (the specified diameter) when measured correctly:

https://www.law.cornell.edu/cfr/text/49/571.139

IF they measure a true 36.5, then rounding up to 37 would be reasonable, and the industry norm. However, @SadRobot says they measure 35.5 inches mounted, and the attached review has them measured less than 36 loaded and unloaded. Thread after thread on various websites measures them out at less than 36”.

I’m not picking on BFG specifically, as all tire brands have a real height less than advertised - but it *seems* like BFG KO2s run smaller than other 37” tires.

As to why there are no class action lawsuits over this: TRA regulations allow up to a 4% deviation in true tire size as opposed to what the manufacturers say the tire size is.

 

[KHR Racing]

IF they measure a true 36.5, then rounding up to 37 would be reasonable, and the industry norm. However, @SadRobot says they measure 35.5 inches mounted, and the attached review has them measured less than 36 loaded and unloaded. Thread after thread on various websites measures them out at less than 36”.

I’m not picking on BFG specifically, as all tire brands have a real height less than advertised - but it *seems* like BFG KO2s run smaller than other 37” tires.

As to why there are no class action lawsuits over this: TRA regulations allow up to a 4% deviation in true tire size as opposed to what the manufacturers say the tire size is.

BFG tires = pretty decent tires. In my 50+ years in offloading they have been the number one brand that are the biggest exaggerator’s of their tire height. Nothing new here. Everybody has discussed this for as long as the Internet has been around……. But without a doubt, still a pretty darn good tire.

 

[Wabujitsu]

BFG tires = pretty decent tires. In my 50+ years in offloading they have been the number one brand that are the biggest exaggerator’s of their tire height. Nothing new here. Everybody has discussed this for as long as the Internet has been around……. But without a doubt, still a pretty darn good tire.

Robert, that is good to know! I wasn’t commenting on their quality, but rather the height measurement exaggeration.

 

[KHR Racing]

Robert, that is good to know! I wasn’t commenting on their quality, but rather the height measurement exaggeration.

I understand and 100% agree with you.

 

[azwjowner]

IF they measure a true 36.5, then rounding up to 37 would be reasonable, and the industry norm. However, @SadRobot says they measure 35.5 inches mounted, and the attached review has them measured less than 36 loaded and unloaded. Thread after thread on various websites measures them out at less than 36”.

I’m not picking on BFG specifically, as all tire brands have a real height less than advertised - but it *seems* like BFG KO2s run smaller than other 37” tires.

As to why there are no class action lawsuits over this: TRA regulations allow up to a 4% deviation in true tire size as opposed to what the manufacturers say the tire size is.

I've measured my KO2s using the protocol in the federal regulations and they were dead on. But that was a smaller size, not a 37 (though I have no reason to expect 37s would be different). I'd love to measure a 37" but it's not a size I'll be running anytime soon. As far as those other measurements, I doubt anyone is measuring with a steel tape measure around the circumference on a tire mounted but not under load, lying on its side, etc.

 

[SoK66]

Ok personal experience here. The big step up from stock tire size at 32-33” is to 35s. The step up from. 35 to 37 is barely noticeable. From the seat of the pants if your power/gearing sucks with 35s the suck factor change is barely perceptible 35-37. The cost difference is usually moderate. If you want 37s get ‘em and work it out from there.

 

[Wabujitsu]

I've measured my KO2s using the protocol in the federal regulations and they were dead on. But that was a smaller size, not a 37 (though I have no reason to expect 37s would be different). I'd love to measure a 37" but it's not a size I'll be running anytime soon. As far as those other measurements, I doubt anyone is measuring with a steel tape measure around the circumference on a tire mounted but not under load, lying on its side, etc.

I imagine a cloth tape would be sufficient. I have one, and measuring the spare tire is easy enough - but I don’t have KO2s.

I realize this isn’t a big deal; fitment, RPMs, MPGs, gearing, etc. is more important. Heck, almost every devoted female companion (of a man) says “Size doesn’t matter!”

The tire-size advertising is a pet peeve of mine, and I realize my pet peeve is ridiculous to others.

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