Join Date: Mar 2008
Location: The 'Wack, BC, Canada
Bikes: Norco (2), Miyata, Canondale, Soma, Redline
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Originally Posted by bikeformoney
I could get more from it, but since the gauge seems to only know how much air I put into the tire, instead of the total combined air in the tire, I don't want to over do it because when it says "75 psi" and the tire feels hard and the handle is more difficult, just don't want to puncture the tube with too much air, not knowing the actual air pressure I am using
You're over thinking the issue.
Assuming the valve is opening properley the pump will never generate more pressure than what is in the tire. The pressure you see the needle stabilize at following a pump stroke is what is in the pump and the tire. They are at the same pressure.
And the pressures do not "add up". What you see at the end of a pump stroke that TRANSFERS AIR
to the tube is the same as what is in the tube. Note that the first pump stroke or even second one may not build up enough pressure in the connecting line to actually transfer air into the tube. Until you hear the honking sound of air flowing through the valve the reading on the pressure guage means zilch.
75PSI in a tire is darn hard to a hand trying to guage pressure with a pinching action. From around 60 to 70psi the tire gets so hard that a pinch test is no longer meaningful in any way whatsoever. At that point you need a guage to measure the pressure.
And finally I can't imagine a floor pump that won't go well past 80 psi unless it's a skinny 10 year old pushing down on the handle and at 80 the back pressure is lifting him off the ground. If it's leaking or something else then it is faulty.