I have done the chalk test twice on the tires of my F350 and have had poor results. I used a thick piece of sidewalk chalk and put a heavy band across all 4 tires. I drove on a flat, paved high school parking lot.

If I drove more than about 100' all the chalk was gone. If I drove less, little or none wore off. If I made a gentle turn, the chalk also disappeared. I considered using white latex paint on a mini paint roller and letting it dry....

Worse, while some tires were at 50 and some at 70 PSI, the chalk wear was so indistinct as to tell me nothing about these pressures. My conclusion was this: If you had one tire at 20 psi, and another at 125 psi, you might see a wear difference in the chalk pattern. Not very useful.

For all you chalk-test users, what do you see that tells you should increase or decrease the pressure by 10-15 lbs? Presumably, this is what we are trying to learn, right? I understand the concept, but my execution is tragic.

Steve, the chalk klutz

 

Run fronts at 60 and the rears depending on the load....50psi when empty is what I run.

 

This is a good video that describes the process. HEAVY chalk, slow straight line, no turning of the wheels...