The chalk test is a simple and inexpensive way to make sure you aren’t running too little or too much pressure in your tires. As everyone out there will tell you, use your common sense here. If the test tells you to run at 1psi, there’s probably something wrong. You also have to take into account the width of your tire vs. the width of your wheel, so keep all that in mind when performing this test.
To get started, all you really need is a flat paved area, some side walk chalk, and your tire pressure gauge. I generally run my tire pressure a little on the high side, so I started off at 37 psi as I chalked up my tire for the first pass.
I drove straight forward a few feet, then a few more feet, then a few more feet looking for a pattern as the chalk wore off. If you have a GoProHero 3 or 3+ that you can aim at the tire while using a wifi connection to monitor what it displays, that makes life soooo much easier. Instead of pulling forward a few feet, stopping then getting out and then looking at your tire, you can just glance at the screen while you inch your Jeep forward. I bet you’ll never guess when I figured that trick out. (hint: It’s way after I was done!)
At 37 psi (shown above), the tire is over inflated since there’s no chalk left on the center of the treads but there is plenty on the edges. Break out your trusty pressure gauge, air down, re-chalk and repeat. Next stop, 34 psi.
Nope, 34 psi (shown above) is still a little too much. However, I am heading in the right direction slowly but surely.
32 psi (shown above) is still too much.
28 psi (shown above)… almost there.
Winner Winner Chicken Dinner! 26 psi (above) looks to be just about spot on. See how the chalk wore evenly across the entire tire? As far as the tread is concerned, that should provide even wear over the life of the tire. Personally, I get a little nervous running a tire at pressure that low but based on everything I’ve read and heard and everyone I’ve spoken with, I’m right on the money. If nothing else, the ride is a whole lot smoother with the pressure dropped.