Airing down E load tires.

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ExpeditionArizona

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So I have some KO2s that are E loaded and I was told these can’t air down much due to sidewall heat building up from too much flex.

But can they be aired down for off-road use at obviously slower that road driving speeds. Maybe even 20psi? Just curious if anyone’s ever ran E load tires on their rigs.
 

rgallant

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I run 18 Psi on my Cooper St Maxx off road and for short road speed sections (30 mph), between gravel. The sidewall on those does not flatten much event at 18 Psi, I have never noticed excessive heat or unusual wear.
For reference I am in a LR Discovery II at about 4700 lbs loaded.

I run 38 Psi normally.

18 in the snow

 

MazeVX

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I do have tires with load range E and there could be some truth to what you said. I noticed heat build up with "lower" pressures but only on highway speeds around 70-85mph for longer sections. When I increase the pressure the heat build up does not happen. Can't tell you much about 20 psi as I only very rarely go down that low and if I do I'm driving really slow. But did some driving with 26psi at gravel road with 18-40mph and didn't notice any heat or increased temperature.
 

MOAK

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I’ve run BFG KOs and ATs. Never a problem airing down to 18psi on the trail, but I prefer 20. On the highway it depends on your GVWeight. When I had Jeep’s I ran 32 lbs with great success. Now I’ve a rig that scales out at 7,000 lbs loaded and usually run with 36lb on the front axle & 38 lbs in the rears with great success. By success I mean at least 45k miles when I sell them used and put new tires on. Now, if I were using e rated tires on a dump truck that was constantly loaded down with 5 ton or more I’d be using the maximum recommended PSI, which, correct me if I’m wrong, 80 psi, and thats loading 3,500 lbs on each corner and none of our rigs weigh 14,000 lbs. good luck
 

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I have KO2s. The size I have is only available in load range E. I usually run at 25 or so off pavement.
 
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smritte

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As everyone said, what the tire weight rating and how much you have on them is all the difference. If there's going to be an issue, it will be over 50 mph and even then for an extended time.
The reason for the caution is something called Pyrolysis (spelling?). The tire, if overloaded and or under inflated can cause the sidewall's to over heat. What happens next is the tire somewhat ignites (without fire) and explodes from the pressure that builds. If you have ever heard a semi truck tire explode while driving, that's it.
Having an "E" rated tire means more load support and higher pressure. What people don't tell you is your suppose to drop the pressure into the correct range for the amount of weight you have.
An example is a set of tires i ran on my jeep. The tires were rated to hold 3500# @ 65 psi. The whole vehicle weighed 4700# with around 1250# per tire. I found the proper pressure to be about 30psi. Even tread wear and as good of a ride as those could give. Because I wasn't anywhere near the capacity of the tire, I didn't get excessive heat/flex from the sidewalls.

When people advise you not to run lower pressure, its because they have to assume your near the load rating or their clueless and their parroting what they were told. If your anywhere near the rating on the tire, low pressure, high speed and long distance will be an issue.
 

Dlnuckolls

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So I have some KO2s that are E loaded and I was told these can’t air down much due to sidewall heat building up from too much flex.

But can they be aired down for off-road use at obviously slower that road driving speeds. Maybe even 20psi? Just curious if anyone’s ever ran E load tires on their rigs.
I run a set of Nitto’s (E rated MTs) on my Wrangler and normally run about 38-40 on highway, and 18 off pavement. I do not get excessive heat and the tires wear extremely well.

For the best tire pressures to run on pavement you should use the chalk method to find the sweet spot. For off road lower it enough for your comfort and better traction footprint. Most tires will handle the 18+ pressures for off road (if you have beadlocked tires you can go significantly lower), but you should feel good about it. You could always start out higher then lower it after you hit a few trails to see where you’re comfort level is.
 

ExpeditionArizona

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I’m running em on a ‘16 F150 and they are 33s. I usually run em about 45psi on Highway just cause my truck pings for “low tire pressure” at anything less than that.

I’ve aired em down to 25psi on trail but there was virtually no flex but there also no weight on the vehicle minus me and a passage.

I have a set of 33in KO2s on a CJ5 but those are C load and they flex very well.
 

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I personally run KO2s in E-load as well. On road yes they definitely heat up a lil on the high way but all tires do. Off-road I've gone as low as 15PSI and only really notice them heating up if I'm running fast >20MPH but that almost never happens normally i maybe see them heat up enough to go up 1psi off-road. Even at 20PSI i get good side wall deformation around rocks and notice good traction improvements, see photo:

1627010087267.png
 

Ragman

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I run 18 Psi on my Cooper St Maxx off road and for short road speed sections (30 mph), between gravel. The sidewall on those does not flatten much event at 18 Psi, I have never noticed excessive heat or unusual wear.
For reference I am in a LR Discovery II at about 4700 lbs loaded.

I run 38 Psi normally.

18 in the snow

How do you like those tires for combined road and trail use? I will be looking at tires shortly and I see the 35s are D-rated.
 

Ragman

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I run Cooper STT Pro 35s on my JKU and AEV suspension. If I recall AEV recommended 28 pounds but I run 32 normally for road use and have 35k miles with no issues.
 

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We run Es on our Ram 3500 diesel with a Lance 650 camper. We will routinely air down to 40 lbs on gravel/dirt and down to 25 in soft sand. No issues, no worries. We know other truck campers that go down to 20 with no ill effects. One time our air pump failed and we had to run on 30 lbs for 30 miles of highway to the nearest gas station with an air pump. We just sucked it up and kept the speed down to 45 max and had no ill effects, plus had more time to enjoy the countryside. And then we purchased a better air pump!
 

rgallant

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@Ragman I like them , they are hybrid AT/MT and work well in the Pacific Northwest. These are my 2rd set in 5 years, had a set on an R50 Pathfinder prior to the Disco.

  • They are decent in the rain, on pavement and not too noisy.
  • Off road they seem to provide good traction, and clear reasonably well.
  • They work as well as any other M&S in the snow, they have given me no issues.
  • I avoid deep mud but they seem to work in what mud I have a passed through, slimy black crap about 8 inches deep for 200 meters
Most the offroad here is hard pack or rocks, some same and mud, the tires have never been a cause of lack of traction for me.
 
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R M Anderson

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At trail speeds lower pressures won’t over heat the tires. Good practice is to feel tires and wheel hub when making periodic stops to gauge temps. I run my KO2s E around 20psi with occasional 16 for rockier areas. The reduced vibration and increased traction are much improved with lower psi. Wouldn’t run highway speeds w low psi for safety.
 

Outdoordog

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Oof, I may be airing down too much....
I have bfg km3s (285 70 17) and have aired down to 10 psi on many occasion (2016 jeep wrangler 4 door).
Usually on road it's about 36 psi.
 

9Mike2

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Oof, I may be airing down too much....
I have bfg km3s (285 70 17) and have aired down to 10 psi on many occasion (2016 jeep wrangler 4 door).
Usually on road it's about 36 psi.
If you haven't had any problems, don't worry...I run a lot of sharp rocks and am scared of a rip in the sidewall..
 

LostWoods

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Another with E-rated KO2s... around 6k truck weight and 18psi on the trails have not been a problem as long as I'm not trying to haul ass.
 
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