Discoverer AT3 33x12.50xR15: What is the correct tie pressure?

JeepLS1_27

JeepLS1_27

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Joined
Jan 29, 2019
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Location
Huntsville, AL
Hey guys, just got brand new Cooper Discoverer AT3 33x12.50xR15 for my 98 Jeep wrangler 2.5l. I have a 4'' lift but nothing fancy other than this. My question is what is the correct pressure for these tires since the wrangler is much lighter than a truck? I noticed when I dropped it off to be aligned the sides of the tire had no gravel powder marks for ~1'' indicating they have too much pressure. So it didn't pass the "chalk test" and I don't have a way of doing this test at home.

I just want even tire tread :)

Thanks in advance!
 
Don't bother with or rely on the "chalk test" which nearly invariably always results in a grossly underinflated tire. If those new tires are Load Range C, which is appropriate for a TJ, your correct tire pressure is 26 psi when the Jeep is lightly loaded, 28 psi when the Jeep is fully loaded with people and/or gear.
 
Jerry Bransford said:
Don't bother with or rely on the "chalk test" which nearly invariably always results in a grossly underinflated tire. If those new tires are Load Range C, which is appropriate for a TJ, your correct tire pressure is 26 psi when the Jeep is lightly loaded, 28 psi when the Jeep is fully loaded with people and/or gear.
Click to expand...

X2 to this.
 
Jerry Bransford said:
Don't bother with or rely on the "chalk test" which nearly invariably always results in a grossly underinflated tire. If those new tires are Load Range C, which is appropriate for a TJ, your correct tire pressure is 26 psi when the Jeep is lightly loaded, 28 psi when the Jeep is fully loaded with people and/or gear.
Click to expand...

I put 26 in them. Edge of tires still don't touch by about 3/4'', if this an issue?
 
JeepLS1_27 said:
I put 26 in them. Edge of tires still don't touch by about 3/4'', if this an issue?
Click to expand...
No. There are few tires designed for 100% of the tread to be on the ground. That's the problem with the chalk test. If you deflate the tires so much that all of the tread is on the ground they're grossly underinflated.
 
Keep an eye on the edges of the tires after some cornering. Personally I air mine down to the point where they wear all the way to the edge when turning but so that they don't touch on straight roads. IE if I pull in my concrete driveway through the 10' of hard packed dirt between it and the road the sand does not touch the edges of the tire by a bit but I can see by the tread that they wear when cornering.

If you run them too low the corners of the tires will get a soft rounded over look to them.

Too high and the corners will never touch.

The trick is to find the happy middle ground so you get to use all of your tread rather than wearing the middles out. (IMO) Secondary benefit is it rides better with less pressure.
 
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