Then after you've found the certified and calibrated tyre pressure gauge, forget about that, go back to your Aircraft and have a look at the Tyres, do they look pumped up? Excellent, continue as you were....
No offence intended Sunfish
it honestly is one of those things where if it's wrong you'll see it, if it looks a little low grab a compressor and give it a pump up, nothing scary about a GA Aircraft Tyre, they're nothing special really when it comes to inflating them. Just check the pressure required and fill to that with the compressor.