DougG

This is not a big deal, but I just wanted an opinion. I lowered our bikes from the rafters the other day and of course was ready to check and air up the tires. What I noticed was that my wife's tires were down about like I'd expect, as was my front tire, but my rear tire was totally flat. I have a compressor and top up our tires before almost every ride and had no tire problems at all last year.

So should I be proactive and replace the rear tube? Or was this likely just a slow valve-stem leak that persisted over the four months that they've been stored? This is one of those slime-filled tubes (not my choice!), and I've had suspicions that that stuff can get into the valves and affect them (some of it often spurts out just when I put a guage on the valve).

Doug

cascade168

Just refill the tire and keep an eye on it for a few days. Tires loose pressure over time due to osmosis. Those little air molecules just squeeze their way through the rubber. Yup.

Losing a couple of lbs in a day or two is not unusual. That's why one of the best pieces of advice you can give anyone is to pump up your tires before every ride. If you find that you ride every day and your tires are not losing any (appreciable amount of) pressure, then back off and pump them up less often. But, if you are believer in Murphy's Law, you will get a slow leak on the same day as you pump them up and the next day (when you don't top them off), you will get the pinch flat and maybe dent your rim.

I would not think of a ride without topping off tire pressure. It makes good sense for so many reasons.

Your slime tube may require a certain minimum pressure to be viable. It may be that when it gets below that minimum that it goes flat in a hurry. Again, I say to just fill it up and keep it topped off.

juicemouse

That would be impossible for either you or us to tell at this stage. It could have happened the day after you hung them up or it could have happened slowly over 4 months time. They're both possible. The way for you to find out if the tube is still useable is to inflate it and check it every once in a while. If it still has reasonable pressure after a day or two, you should be good to go.

lrzipris

I have no idea what impact the slime would have, but you could remove the tube, inflate it and submerge it in water to see if there's a leak.

spunkyruss

Some retailers warn against using a tire pressure guage on a slimed tire, due to slime gumming-up the guage. I suspect that slime has the capacity to similarly gum-up a valve.

You may be able to remove and clean or replace the valve core if the tube has a Schader valve, or one of the removable-core Presta valves (I've never seen one, but I understand that they have wrench flats on the threads that the cap screws onto).