Originally Posted by
MudPie
... I always felt the mere act of measuring pressure decreases the pressure in the tire, especially a road tire...
Yes. With a pump gauge, you read the pressure as the pump piston is moving down and air is going into the tube. Do the last few strokes slowly to get an accurate reading. Once the piston of the pump stops moving and air stops flowing into the tube, the presta valve can close and you're left reading the pressure in the pump hose, not the tire.