Am I overfilling my tire?

Question

I just bought a floor pump with a pressure gauge.

After I pump up the tire to its appropriate pressure, I want to use the guage the next day or after a ride to check the pressure. But when I do this, the guage shows a low reading and it takes two or three pumps to get it back to the right pressure.

Am I overfilling my tube if I do this?

Answer 1

Road tire or mountain? I'm assuming a road tire, because the volume in a MTB tire is far greater than a 700x23C tire.

The volume of air that is displaced by the air hose on the pump is partly responsible for this. On a MTB tire that volume is so insignificant that you won't really notice a change, but on a road tire it could show as much as a 10 PSI difference.

So if you like your road tires at 110 PSI and inflate them to that level, then they're at 110 PSI. If you IMMEDIATELY atach your pump again, you'll see just how much the volume in your pump hose displaces and how much pressure you "lost" when you attached it.

You already KNOW that you just inflated to your desired pressure, and now you know how much your pump "drops" when you attach it.

So you may not be low at all, it's jus the effect of displacing a certain volume of air at a certain pressure.

Answer 2

Another important things to remember is that the gauges built into pumps are notoriously inaccurate, and they are nowhere near accurate enough to get a straight reading when we're talking about p.s.i. in the single digits. A seperate pressure gauge will give you a much clearer reading. I have a digital one by Planet Bike which I purchased for $10.00 (USD) that works a treat. I also have another, mechanical one that I bought at a car wash for a dollar that is also totally serviceable. Someone mentioned using 'feel' to judge when their tires are correctly inflated, and if you have a lot of experience with that particular tube and tire combo, it's not a bad way to get a ballpark figure for inflation. I would say your problem here isn't over-inflation, it'san innacurate gauge. Yes, Boyle's law is in effect because we're on Earth, but really doesn't have much of a day to day effect on a bicycle inner tube. Definetly be careful with over inflating a bike tire, this is especialy true if we're talking about a high P.S.I. road or track tire. If you over inflate one of those suckers, and it blows off the rim, you'll definetly be in pain, and you might break a fingeer or two. It's almost initiation for rookie bike mechanics.

Answer 3

Possibly. Your pump is not designed to be an actual tire pressure gauge. It's meant for you to be able to pump up your tire to the appropriate pressure without testing the pressure with a pressure gauge 2 or 3 times to get it right. It will take 2 or 3 pumps for your pump gauge to show the actual amout of air in the tire. While doing this, you probably are pushing extra air into your tire. While it won't cause immediate damage, it may cause problems in the future. Instead of using your pump gauge to check air pressure, I would suggest that you go out and get an actual pressure gauge. They are very inexpensive and are a lot easier than using your pump gauge.

Answer 4

Air pressure will read differently depending on the temperature of the tire.

You might have a slow leak somewhere either in the tire itself or with the rim seal.

Answer 5

Actually no. There is a law called Boyle's or Charles law that say when the temperature goes up, the pressure goes up. When its cold it goes the opposite. So probably the room is cold wherever your filling the tire with air.

Answer 6

do no longer overfill your tires. The radius may be better, so which you will get greater desirable mileage, notwithstanding that is not any longer very well worth the prospect of having right into a ruin for something stupid. Overfilled tires positioned on basically on the midsection, on condition that it quite is the area in touch with the line. In an emergency provide up, that little bit of better could make a super distinction. do no longer ignore that air acts as an proper gas, so the stress will enhance because of fact the tires warmth up, and the tires warmth up as they are pushed. this could enhance the possibly-hood of having a devastating blowout. as quickly as a blowout occurs, you have little or no administration, except you're an extremely experienced driving force. top off your tires to approximately 30 psi till now you force on them, so as that they have got room to strengthen, yet they are in reliable touch with the line the completed time.

Answer 7

i always go by the feel of the tire. if you squeeze the tire in your hand, it should barely compress inward. push down on the handlebars and on the seat- you should notice how the tires get wider at the contact patch with the ground. keep that at a minimum.

Answer 8

it looks you are learning how to use properly the pump...not all pumps..pump direct...and some air..outflows...
nothing to worry about...have a nice ride

Answer 9

i think we experience the same thing,