IROK size question

[SHoppe715]

I'm doing more web-wheeling and future scheming for the GB. I don't want a bigger diameter tire because of the gearing I've got and I want to mount the spare under the bed without it hanging down too far. A HMMWV tire will work well for the spare, but I want a wider / softer footprint.

So I was comparing the 36/13.50-16.5 and the 37/14.00-16.5 bias ply IROK and it seems the 36" is bigger in all dimensions except weight, price, and approved rim width. It's supposedly about 1/2" taller with 1 1/2" wider tread, but mounts on a narrower rim (my rims are 9.75" wide), is 13lb lighter, and cost $10 less per tire. Am I reading this stuff right?

http://www.4wheelparts.com/Tires/IROK-Bi...&t_pl=3866

http://store.summitracing.com/egnsearch....wordSearch

[TJVigilante]

Here's a rather simple discussion on it from Pirate4x4:

http://www.pirate4x4.com/forum/showthread.php?t=655710

Pretty much the numbers from Interco are BS.
In another thread they mention that the 37s have a different tread design and are more square than the 36's. Careful of the language...
http://www.pirate4x4.com/forum/showthread.php?t=636148

Here's a quote from yet ANOTHER PBB thread:

I currently run 36x13.5x15 Irok bias ply tires(that are worn out). I was shopping around for replacements and really liked the IROKs so was looking for the same tire.

Now they have 2 tire sizes that are almost identical. A 36x13.5x15 and a 37x14x15. the exact dimension and weight numbers are slightly off and I couldn't understand why they would come out with two tires almost identical.

So I called Interco Tire and asked them. The answer? The molds that are used to make the tires are slightly off due to expansion/contraction of the mold during it's manufacture. That's the only reason they could give me. So I'm guessing, as demand for the tires increased, they had to create a 2nd mold to make twice the # of tires. But the mold came out slightly different.

I still don't like the answer I got but they said that was the only one they could give me.

My own guess is they originally mis-stated the size of the 36" tire(since it's diameter is 36.8" it should have been stated as a 37) and may have been losing a lot of sales of folks wanting to go to 37s. So they made a slight variation to their mold and called it a 37. Just a guess.




I now have a set of 37x14x16 bias plies. Looking at the tire, it doesn't have as much of a donut(sidewall bulge) effect that the 36x15s have but that could be due to rim diameter difference. The tread on the sidewall looks thicker and the main part of the tread doesn't have the large stickouts on the outter lugs the 36s had(I liked those large stickouts). So it appears the mold might have a few minor differences besides just the explanation I got from Interco.

Here's a picture from a Jeepforum thread:



37 on the left, 36 on the right. both on 15x8 wheels.

[ZMonster]

Ah hahahha, the irok's are spreading like a wildfire!!!!!