36x13.50 Irok Trail Pressures

BUCKETOBOLTS

BUCKETOBOLTS

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Joined
May 4, 2005
Location
Faith, NC
I've made 2 trips to Uwharrie on my Iroks. The first trip I did not air down with the tires a 20psi. Needless to say it was a rough ride. This past trip I dropped to 10psi and she rode much smoother. I did not have any trouble with traction, well except for the ledge on the Daniel trail where I tried to climb the rock from a standing start. I backed up about 3 feet and hit it at a slow roll and up she went. What pressures do you run on the trail? I think I might drop to about 6lbs on the next trip.
 
I run 6 lbs, but I have beadlocks. I'm going to play around with 8 in the rear, 6 up front this year.
 
I'm going to try this method, and it makes a helluva lot more sense than "what pressure do you run?"

take a right angle square, put it on the ground, and the other edges against the sidewall. Now move it back 1/2". Now air down until the tire starts to push on the square. stop there and check your pressure.

Here's why.. pressure is largly determined by the weight on that tire. "aired down" to a Hummer and "aired down" to a zuke on the same tires are 2 totally different pressures, neither of which help you one bit.

In the case of my rig, I've got vastly different weights on the front & rear axles, so while I might run 8psi int he front to get the tires to wrap, the rear might have to go as low as 3-4, because there's much less weight on them, but that doesn't help you either.

Also, as tires get more broken in, they can be run with more pressure, and flex the same. after I grooved & siped my SX's, they just about folded over on themselves at 6psi.. running 10 made them behave like they did previous to the grooving at 6..

That said, as a guess, I'd try around 8 on yours (I think youv'e got locks, right?) and see how they grip.
 
Thanks Rich, I like your theory method of tire pressures. I don't have locks. I don't think the Iroks need to be cut, the tread is much smaller in lug size than my TSL-SX's were. I'm not sure of the weight, but I believe it is probably around 3500lbs. I'm very glad I ditched my ProComp MT's. When I dropped to 10psi, the sidewalls only bulged an inch or so. I didn't even notice alot of body sway. Swampers ussually have a pretty tough sidewall.
 
I run 4-6 in the front And 2-4 in the back most of the time. If it some thing easy like Uwharrie I'll run 10-12.
I have a heavy CJ that needs a diet.
 
you running bias-ply or radials?

8" rim or 10" rim?

I run the 36x13.50 radials on 15x8...and have been on the trails three times...

the first two at 8PSI, the third at 7PSI...there was a big difference (visually) in dropping that one pound...

can't tell exactly, but here's 8PSI:

IMG_4251.sized.jpg



and here's 7PSI:

IMG_4513.sized.jpg



I also sanded the powdercoat off the rim where the beads sit, and used bead sealer on them...

Figure I ought to be able to run 5-6PSI if I wanted to...I think that's what Andy was running in the Commanche with the same setup...

Greg
 
This past weekend at Tellico on brand new beadlocked 39.5 bias IROKs, I ran 1psi, yup, one ! And they just started to bulge. I suspect as the sidewalls break in, I'll come up to 3-4psi, but I couldn't beleive it. 1psi. or thats the lowest my guage would read. Follow Rich's suggestion of watch for the sides to just start to bulge, what ever pressure that may be.

JB
 
BUCKETOBOLTS said:
I'm not sure of the weight, but I believe it is probably around 3500lbs.
Click to expand...

Probably more around 4500lbs or more...
 
I am running 7psi in the front and 6psin in the rear on my toyota pickup with no beadlocks. It took them about 5 or 6 good runs before they really started to break in.
 
Like everyone said, weight is a big factor. As well as bead-locked or not, and also tire width vs wheel width. the less difference in tire/wheel width, the more PSI you have to run. Fronts usually more because they turn and will peel of more so than the rears.
 
I run a 15x10 wheel. I'll try to get a pic of 10psi this evening. Like I said I didn't have any traction troubles the last outing, I thought that at 10psi the sidewalls should have bulged a little more.
 

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how many runs does it take to break them in? i was a little disapointed in how they ran on my first trip out, started the day with 10psi, then later in the day droped to 7psi, and couldn't see much of any difference. at 10psi on my wifes trxus MT's they were flexing like mad. :mad:
 
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