WHAT TIRE PRESSURES DO YOU RUN?

[mrchips]

This has been an interesting debate.
I have BFG KM2 35" on my LJ and for street pressures I use 26 psi. How I came to this .

Taking a piece of chalk and making a unbroken line across the tire, then moving rig slowly a hundred feet or so down the street, large parking lot is also good, stop and observe the line.

If it is wiped away in the middle you have too much air pressure,

Wiped off on the outer edges not enough air pressure,

By adjusting the pressure so that the chalk line wipes clean across the whole tire, I have now reached a good target air pressure where the whole tire surface is making a good contact pattern with the road surface.

I have had less time having to air up from 10-26 psi on such a large tire, and also the ride is allot better. This lower pressure equates to the larger air volume that the tire can hold, and also the weight of a Jeep LJ vs a full size truck.

I will say that I do add a little more pressure when I am loaded down and pulling my trailer.

My tires wear well and I have had no problems at all.

Appreciate any input.

 

[marshal]

i run 26/28PSI on my 37" KM2s, but air down to 10PSI offroad

i hate my KM2's, but otherwise the pressure works well

 

[aristobrat]

AFAIK, since everyone's rig has a different weight doing the chalk test is about the only way to determine the PSI for your rig.

The chalk test on my JK running 35" KM2s showed 28 psi.

 

[Judoka]

I run 18 on my 13 jku off road. I like to be low enough to let my tires form around the terrain so I get good traction.
I run the factory recommended 37 psi on road.

 

[brianjwilson]

35x12.50r17 km2s on my unlimited, run them at 26-29 psi depending. Usually closer to 26 usually, closer to 30 if I'm going on a long highway drive. Off road 12-18psi, again just depends. The km2 has a soft sidewall, I rarely go below 15 on rocks since the sidewalls will still pinch up to the wheel. Lower in snow/mud.

 

[Chuck59]

I run 35 lbs on my daily driver, Cooper S/T 31X10.5X15's.

 

[05nissanXterra]

305/70R16 GoodYear DuraTracs I run 28-30lbs street/ trail, and 20lbs on rock


Sent from my iPhone4 using Tapatalk

 

[mrchips]

I have noticed that too, so many guys running larger tires with tire pressures that are so high, and then they have these small air pumps that take forever to get them back to street pressures.
Oh well live and learn.

 

[Glenn D]

I run 33x15.5x15's Fun Country's on 12" wide wheels on a '94 YJ.. at 22 lbs front and rear... tire pressure must be established on tires based on load... using the chalk is a great way to get to the right number... a few lbs make a world of difference in tire life, handling, traction and all that we do to have fun... When I head up to Big Bear to wheel, the tire pressure gains causes a lot of difference in handling... So getting onto the trail at 10 lbs helps a lot... and when I get back down the hill, need to readjust tire pressure again...

 

[nwoods]

On my LJ with 35" KM2's, I ran 30-32psi on the street and about 15 psi on the trail. I had a fairly heavy load, with lots of steel added front, rear and center, plus a winch and often 4 people aboard, plus tools, etc....

The KM2's are a pretty soft tire, but have excellent bead adhesion!

 

[mrchips]

Great pics

 

[IKE2013]

Running 28 on 315 70 17s on a JK 4 door. I aired to 32 and it beat the crap out of me. Way to hard for the street. I aired down to 28 again and is pretty much my target pressure. The tire company states to run 35 or the recommended tire pressure for the vehicle. There is NO way I would try to put 35 and drive around. The chalk method is said to be a very good test too.

 

[wADVr]

Against the grain here, but I run 32psi street on the JK and 35psi on the XJ. 35was necessary on the XJ as it would get squirly on corners (freeway speeds) with the 315/75r16 MTRs(gen 1 not Kevlars) at 32psi, 35psi fixed that handling issue brought on by the tires. The previous set of BFGs had no issues. I have run less to get the jeep home after a trail run but for the most part that is the pressures I have run with good results. I typically get more mileage out of my tires than most without any weird tread wear such as cupping and I also run them down to almost nothing so I see long term results with even wear across the tread.

Potential issues I see with the chalk line method are overheating the sidewalls on freeway driving and tread cupping. I think it is possible to rely too much on the sidewall stiffness to support the vehicle with less air pressure than fully support the sidewall with the manufacturers recommended air pressure. 28psi is by no means low air pressure but having seen the difference from 32-35psi I am weary of running much less than the typical recommendation from the vehicle manufacturer. So many variables; actual vehicle weight, suspension ability to dampen the tires, tire rating, actual tire sidewall strength.. Maybe the chalk line is the best mothod for tuning the pressure?

 

[mrchips]

I have used the chalk line method for the last 7 years, and over 60K miles and never had a tire issue on the road from overheating, and have gotten good wear from the tires.

Great to see other peoples opinions on the matter.

 

[smokeybear]

Here's a quick starter: Look at the factory recommendation for the factory tires, then find the same load capacity in the tire size you currently run. That should be where you start for a fully loaded rig.
http://toyotires.com/tires-101/load-and-inflation-tables
Note the correction factor if you had P tires from the factory.