there are more expensive "pressure gauges" that can handle fluid better. if not. get yourself a couple tire gauge cheapies some place, so if they foul up from gunk of the fluid in tire. you can keep on going. and still have a better regular tire gauge for everything else.
have had issues with rocks, dirt clods, ruts, etc... getting into the tire valve. so as soon as i realize i lost the cheap end caps for the valve stems, they tend to get tossed on to the top of the buy/todo list. before i get a larger issue with the valves stems.
generally i fill tires right up to the valve stem with fluid, with valve located at 12 o'clock position. and then drain a little bit of liquid out., then pump tires up to wanted PSI with air. draining just a little bit of fluid out, so i am not splashing myself ever time i go and check air pressure in fluid filled tires. granted still some fluid gets in valve stem just from rotating tire. but just a little blast, vs trying to connect a garden hose nozzle to a garden hose without kinking the hose or turning off the water, and getting sprayed.
normally do not run MAX PSI in any of my tractor tires, fronts or backs. more so the backs. the FRONT's if there is a FEL (Front end loader) on tractor, and i know i will be using FEL. then tires tend to get inflated to max psi. if to much pressure, make sure valve is at 12 oclock position and let some air out. hopefully only a couple quick burst of fluid comes out, that was in the valve stem. having a rag in hand around valve stem and tool to remove air, can be handy, to keep yourself clean.
loosing a tiny bit of liquid when check tire pressure, not going to harm anything. it is when the tires are say only half full of full of fluid, and the fluid begins sloshing around in the tires, that things could get dangerous on hills. i do not remember what is recommended amount fluid filled tires are, i want to say 78% or 80%. which is basically right to the valve stem when at 12 oclock position.
thanks again.