need help about pumping tires
 

I know this will sound dumb but I'm really clueless. I have a mountain bike with tires that have lost pressure since it's been sitting unused for 7 months. I got a floor pump with pressure gauge and tried to inflate the tires but although the recommended pressure is 40-65 psi, I can't seem to pump them to that pressure. At around 25 psi the tires already felt very hard and the pump got really hard to push. I didn't want to push the pump too hard because I was worried the tires might explode. Should I pump more air no matter how hard the tires feel and just trust the pressure gauge?

Got a pencil guage in your glovebox? See if the readings match.

Typically, tires should be pumped hard enough that if you squeeze them with your thumb, you'll make a small dent, but it will be hard to do. Furthermore, when you sit on the bike, the tires should "squish" a bit around the bottom, but not so much that the rim will ever bottom out by riding. Inflating the tires to this level gives you a comfortable ride, with a minimum of friction.

By the way, it's basically impossible to "explode" a bike tire, since the tire itself is much stronger than the airtight inner tube. The worst that can normally happen is that you will pop a hole in the inner tube, which is easy to patch or to replace (a new inner tube usually costs $3-5). The other problem with overinflating your tires is that it will make the ride very uncomfortable and jarring, because the tire will hardly flex at all as you go over bumps.

Hope this helps you to pump up your tires without worrying too much about the pressure gauge :)

Tires rated 40-65 getting that hard at only 25 psi...hmm, sounds odd. My guess is the pump's gauge is way off, so take mactheknife68's advice. If you don't have a gauge, borrow a pump and see if you have the same problem.

Yes. Get another gauge.

I have a problem within the inflation realm...

I bought a new manual pump, the guage on it goes up to 260 psi. It has a wooden handle (brand new) and I've seen other people at the track with the same pump so I figured it was good...

I just put together a new mavic wheelset and installed some tufo's ... I had to use a valve extender because the stem was not long enough... so I stick this pump thing on it (no latch on the inflation fitting), just a rubber grommet thing in there... I start to pump away and at first nothing happens...

Then it catches and starts to hold air, but it leaks it out almost as fast as I can pump it back in.. I kept fighting it and got about 100 psi into it... after like 30 pumps !! ....

I tried it with the 2nd wheel and had the same issue, what am I doing wrong? How can I fix this?

+1 Ride the bike to a gas station and check it there if you don't have one.

Hose end
 

Sounds like you may not have the air hose end pushed down far enough on the valve stem.

I just posted not to long ago with basicly the same question. I pumped as much air into the tires as I could, yet the pressure in the tires was way too low. Turned out I had a cheap pump, that couldnt pump enough air into the tires. Do you have a good pump. I had a cheap one from Miejers (like Walmart store). If you look through my posts, clicking on my avatar, look at "confused about air pressure gauges".

It was insane trying to pump up my MTB tires to 40 psi with a Walmart Bell pump. Once I got a decent Serfas floor pump, it was really easy to do, and taking it up to 120 psi on my road bike is a piece of cake. The Bell pump is only good for Walmart tires with a max of 30-40 psi.

I just bought a Topeak Joe Blow pump. Nothing beats a good pump...nothing.

Are you sure it's leaking out of the tire? Normally the tire pressure closes the presta valve and the leaking you get is actually out of the pump because of an imperfect seal at the valve stem. Since you are using valve extenders, it could leak out at the chuck or at the extender/valve interface. Many folks use teflon tape on the valve stem when using valve extenders to give a better seal there.

Another possibility is if the valve stem is bent, it might be binding against the inside wall of the valve extender not allowing it to close all the way after each pump.

A pump with a small diameter barrel is much easier to get high pressures. It may take more strokes to reach any given pressure, but you will be sure of reaching the pressure you want.

In tires and love....I'll shut up now.

it's spelled

GAUGE

seriously.