[Rickertsen2]

I didn't know FRIST specd a pressure.

I think you can pretty much rule out and sort of tire pressure or normal pneumatics guage. I doubt those things are inflated to even 2 psi.

You could always order a lower range pressure guage and use the fittings from a float inflator.

I suppose you could always put a piece of plywood on the tube with a weight on it and measure the squish. We noticed that by themselves, the tubes don't change much dimensionally with presssure.