A Tire Knocker

I only gauge once a week to make sure my TPMS is working....but, i have an in cab read out with the pressure of my tires as soon as i turn the key. It also alerts me to problems, so its not as necessary to gauge the tires since they are constantly electronically gauged.

 

I use a 3 pound "mini sledge"; the engineers hammer from Harbor Freight works well, too. If I'm paying attention, I can tell a 10 PSI difference in the tires.

Whatever you use, you need weight. I've found that 3# is about right. You need to hit the tire hard enough to make it ring, and the tire pressure will affect the pitch. Between hearing the ring and feeling the bounce, you can get a really good feel for the tire pressure.

Those billy clubs that the truck stops sell are pretty much useless for checking tires, though they are slightly more useful at that than poking the tire with your toe.

 

The bigger the better. Use a gauge to measure them, 38DD is just about right.