STT Pro 37s Load Range D or E

JoeB-JKURX

JoeB-JKURX

New member
I'm moving from my 35" KM2s to 37" STT Pros. I'm inclined to go to the 13.50x17 because it is Load Range E (likely a stronger sidewall) but am concerned that the ride will be too stiff for my 2014 Rubicon X that has (probably) 800# of added weight through various mods and adds. The 12.5x17 is offered in Load Range D which is what I run on the KM2s and the ride is OK. Any opinions on the various trade-offs would be appreciated. Thx
 
The 13.50's is what I run and mainly because of the range E rating. I just run them at a lower psi like 28 or so.
 
I will echo what everyone is saying as well. I run the STT pro in a 37x13.50 load range E on my 4dr and I’m probably close to 700 lbs heavier than stock. But that’s just s guess. I run 28-30 psi and it’s fine on the roads here in salt lake. Trail pressure is 8-12 depending where I’m at.
 
I'm running the 37x13.50's Coops too. My CAT scale weight fully loaded is just under 6000#. I run 26# highway, but our roads in PA suck donkey dick, so there's that. Best starting point to figure psi is to do the chalk test. You can fine tune from there if you want :thumb:
 
That’s the only thing I don’t love about jumping to 40’s. The STT’s (as well as Nitto) go to a C rating. Does stiffer sidewall necessarily mean stronger, though? Ply is still the same right?


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I was wondering the same thing. The BFG 39-13.5s go to a load range c as well. Are the plys thicker on the larger tires? Is that why they don’t use as many as the Ds and Es?


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wjtstudios said:
I was wondering the same thing. The BFG 39-13.5s go to a load range c as well. Are the plys thicker on the larger tires? Is that why they don’t use as many as the Ds and Es?


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I think this is more because of the volume of air in the larger sizes. Same reason that when you go bigger your running lower pressure to support the same amount of weight. I think if they increased the ply it would put the weight capacity into an un usable range. Plus these larger tires are already really heavy to begin with so I'm sure that is also taken into consideration.


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QuicksilverJK said:
I think this is more because of the volume of air in the larger sizes. Same reason that when you go bigger your running lower pressure to support the same amount of weight. I think if they increased the ply it would put the weight capacity into an un usable range. Plus these larger tires are already really heavy to begin with so I'm sure that is also taken into consideration.


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Makes sense. Is there more risk of sidewalk damage with a C verses a E range tire?


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wjtstudios said:
Damn autocorrect. How about sidewalls.


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The sidewalls are tougher on the Es but they are also heavier. I can tell you that my jeep weighs in at almost 6,000lbs and my 37/1350r17 Es barely bulge at 12psi they do great at absorbing rocks etc though. I think that if you wheel lots of very loose sand and or mud the Cs would have an advantage, and if you are on more sharp/jagged rocks than the Es would give some more piece of mind.


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