Bicycle Mechanics - Trouble Inflating Tires with Slime tubes

Hi all -

I commute by bike to work most days of the week and got a flat a few weeks ago. I replaced the tires with Slime Tubes but for some reason I can never get adequate pressure on the tires. No matter how much air I put in there, they always seem to sag when ridden. There's obviously no leak since the slime stops leaks, and the pressure never seems to change after I've inflated it...it just never gets to a maximum level when I keep inflating it with are (using a hand pump). I do hear a click in the cap of the pump whenever I'm inflating it and it's near maximum pressure.

Never seemed to have this problem using regular tubes. Anything I'm doing wrong?

The only thing I can think of is that the Slime might somehow be affecting the valve causing the hose pressure which the pump reads to be higher than the tire pressure. I've seen this happen with Presta valves which can get stuck closed and need tremendous pressure, or manually opening (burping) so they'll open to admit incoming air.

With Shrader valves the pin on the thumblock is supposed to keep the valve open. Is it possible you're not pusing the pump head on far enough, or that maybe at half pressure is slips back a bit letting the valve close?

What is the max on the tires and what does the gauge say the pressure is at when you can't get any more air in?

Thanks all. My hand pump doesn't have a gauge. But I stopped by the local bike shop after work and got a Presta adaptor and then inflated my tires with an air compressor. I was able to get a MUCH better tire pressure now.

Don't over inflate your tires. They tend to fail explosively if over-inflated. A little over max recommended is usually OK, but it's your well-being, and decision to push it. Also, rims can have a lower maximum recommended tire pressure than the tires. Might be worth looking into if you've put narrower tires on than the bike came with.

Though rarely is the maximum pressure a tire can hold the appropriate tire pressure for your use, unless you're heavy on narrow tires.

"Anything I'm doing wrong?" Using the Slime tubes for one. They are heavy, and have an anoying habit which you have discovered. The valve will clog from the inside, because it acts like a leak. You have to take the valve core out, and (try) to clean the inside of the valve stem with a q-tip and water. You may have to replace the valve core, as it too will be fouled with dried or semi dried Slime. I tried a slime tube once, it didn't last the summer because I got so f'n sick and tired of cleaning the valve every time I wanted to add air.
Unless you get a lot of flats, get some regular tubes.

If you air up every other day or so the valve is more likely to stay loose. Also air up in the morning after making sure the valves aren't at the bottom of the wheels swimming in slime when you park the night before.

There are a couple of tricks to using slime but it's really no problem once you get used to it.

I noticed you're running presta valves. Just make sure you burp the valve before connecting pump head. Just give it a little tap and listen for a sssst.