Yours might be a little better than the ones my dad got, because they were cheap and obviously didn't work right.

I think I'll just stick with a dial gauge.

 

Check each tire twice and check'em often is what I was told! In the summer in one day on the current rims and tires the tire pressure went from 40 PSI to 10 psi on the rear passenger tire (20"x10"). It might have been the valve stem and the way it was seated or the fact that they were new and it didn't seal right! But I never had a problem since! Just fun facts