Tire Size Question w/ K02's

[meffie]

Looking into my 37" options, and I read over and over again how BFG K02's run smaller. But looking at actual specs, per manufacturer specs, the K02's have a diameter of 36.5, Nitto Recon Grapplers are 36.54, Ridge Grapplers are 36.77, Toyo Open Country AT3 are 36.5.

So where is the size diff in the K02's? Am I missing something here? These all seem to be pretty darn close to me.

Thanks.

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[RobWTX]

I have no idea, other than maybe once aired up and the vehicle weight is on them, the KO2's squish down a little more than the others?

 

[meffie]

I have no idea, other than maybe once aired up and the vehicle weight is on them, the KO2's squish down a little more than the others?

Yea I'm at a loss here as to why folks say they run small. By spec anyway, it would appear all the majors seem to run spot on.

I had originally strayed away from the K02's because of this "size issue", but now I'm looking at them again since they are the only C load option out there I can find, and I don't know that I want to add an extra 11# per tire going D load from Nitto etc

 

[RobWTX]

Take a gander at the falken wildpeak at3w, heard good things about them, and I believe they are a C rated tire also.

 

[RagnarKon]

Honestly I think people are just uneducated about tire sizes.

The Euro-metric tire sizes are measured based off of the finished tire. Meanwhile the American sizes are based off of the mold and not the finished tire. Why?? I have no idea, probably the same reason why a 2x4 is actually 1.5" x 3.5". People assume when you buy a 37x12.50R17 tire, you are going to actually get a 37" tire when all is said and done, but that's not the case.

Same thing happened when the Bronco first launched. A bunch of people showed up on this forum and complained that the "35s" that came with the Bronco aren't actually 35s.

 

[meffie]

Honestly I think people are just uneducated about tire sizes.

The Euro-metric tire sizes are measured based off of the finished tire. Meanwhile the American sizes are based off of the mold and not the finished tire. Why?? I have no idea, probably the same reason why a 2x4 is actually 1.5" x 3.5". People assume when you buy a 37x12.50R17 tire, you are going to actually get a 37" tire when all is said and done, but that's not the case.

Same thing happened when the Bronco first launched. A bunch of people showed up on this forum and complained that the "35s" that came with the Bronco aren't actually 35s.

While I certainly understand the American "these 37's are not actually 37's" idea you're discussing here, I am not sure that is what the folks are saying. I mean I suppose it could be, but in almost any thread in the forums you read where folks talk about the k02's, they say they run smaller than the rest of the tires, which would imply, to me anyway, that there is something specific about the k02 thats undersized, vs a mold to actual difference of all tires.

Maybe I'm misinterepting the complaint, but all things being equal, from what I see all the tires are basically the same size.

Now I guess if the K02's actually come out of the molds at say 35.5 instead of the listed 36.5, then sure, that makes sense. And I guess that's why I have asked this question. I don't want to give up any ride height, but if they are a consistent size across the brands as it would appear, then that wouldn't be a factor

 

[meffie]

Take a gander at the falken wildpeak at3w, heard good things about them, and I believe they are a C rated tire also.

Looking at their website, the 2 37's they have available show D and E load rating respetively. Where did you see C rating on them?

 

[RobWTX]

Looking at their website, the 2 37's they have available show D and E load rating respetively. Where did you see C rating on them?

Crap, I can't read. Did not see you said 37's, lol.

 

[Jsb]

ko bfgs are also lighter in weight for the C rated version 66-68ibs I believe which is something to consider.

 

[jzweedyk]

I have 37" KOs on my 2 door and I love them. They are quiet on the road and perform well off road in loose gravel and rocks. I try not to do mud, so I can't really say how good they are in that. If they were much bigger they would rub. I have the Icon suspension but at full lock off camber they do rub a little. Personally, I think BFG makes the best off road tires.

 

[LivingMyVestLife]

My BFG 37's measure exactly 35.5 inches on the car but I only put 36-38 psi in them, so maybe that make them squish more?

 

[CarbonSteel]

37x12.5x17 BFG KO2's Load Range C on 2019 JLUR that weighed 5700# empty on 17x8.5" wheels.

UNLOADED:

LOADED:

 

[meffie]

37x12.5x17 BFG KO2's Load Range C on 2019 JLUR that weighed 5700# empty on 17x8.5" wheels.

UNLOADED:

LOADED:

Ahh maybe loaded is what folks are referring too? That is an inch under rated size. Maybe the side walls being c rated causes more loaded sag than the others.

That would explain everyone saying the are are shorter.

Thanks for those pictures

 

[CarbonSteel]

Ahh maybe loaded is what folks are referring too? That is an inch under rated size. Maybe the side walls being c rated causes more loaded sag than the others.

That would explain everyone saying they are shorter.

Thanks for those pictures

Keep in mind (and others may have already said this) that no tire matches the advertised size--at least in my experience. With that said, BFG tires are even shorter than most and thus why they are not even close to advertised size.

LRC does allow for more flex, but it was only 3/8" difference between unloaded and loaded or a delta of 3/16" in height. My JLUR was heavy and I thinking that LRD would have had about the same difference.

I went with LRC to keep the unsprung weight down because some of the 37" tires are stupid heavy. Here is a spreadsheet that I did back in 2021 that is likely dated on pricing, but the specs should be the same. The baseline was the 285/70/17 (33") tires that came from the factory on my Rubicon.

Link to 37" Tire Comparison

 

[DbarD]

Looking into my 37" options, and I read over and over again how BFG K02's run smaller. But looking at actual specs, per manufacturer specs, the K02's have a diameter of 36.5, Nitto Recon Grapplers are 36.54, Ridge Grapplers are 36.77, Toyo Open Country AT3 are 36.5.

So where is the size diff in the K02's? Am I missing something here? These all seem to be pretty darn close to me.

Thanks.

I bought the Falcon Wildpeak 37X12.5 mud terrain after I added a 1 1/4” leveling kit for the front. Great tires and look. Bronco Wildtrak w/sas

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