Balloon Tire Inflation

After dragging my plastic tire cart for 2 miles in soft sand ( required my son and I on the cart handle ) I have invested in a balloon tire cart. I need a tire pressure gauge that will measure 3 psi or lower. Any ideas on finding one. And a air pump that will screw onto the tire valve stem.

I use a bicycle pump

I just pumped mine till they were reasonably round. You almost can’t put too little air in. Start low, real low,..and go from there.