Bike tires only inflate up to 30psi with foot pump

Question

My bike has sat over the winter, and the tires went flat.  I used my foot pump to inflate the tires (front and back) and both tires inflated to 30 psi.  I have shraeder valves.  The pump continued to working with the same amount of resistance, but the psi on both tires would not go above 30. I am assuming that since the tires did inflate up to 30 psi, the valve connected, air is getting into the tire, and the pin is not stuck. Maybe I am wrong. Hoping someone else has had this issue and can share the fix.
Update. There is no sound of air escaping anywhere. I left the pump connected to the valve over night, and the psi did not decrease. The Gauge on the pump goes up to 100psi.

Dave Brunker · Answer

I don't think it's likely that there's a problem with the valve or tube. You should check it with a separate pressure gauge and try a different pump.

Chris H · Answer

I'd suspect the pump seals, having had trouble before. I've had this with my Mini Morph, and ended up replacing the O-ring; regreasing is another option and the first thing to try.
Sometimes the inlet seal is OK statically but leaks dynamically when you pump.  The peak pressure inside the pump is considerably higher than the pressure in the tyre, as it has to overcome the valve spring and push air down a narrow tube.    You wouldn't hear the air escaping because it only does so when you're putting in effort and moving parts against each other, so masking the sound.
Sometimes it's a seal where the hose leaves the body, that might need greasing and/or tightening.

Bike tires only inflate up to 30psi with foot pump

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