Rear tire pressure question

NorseMan9 · Post by **NorseMan9** » Thu Nov 16, 2006 10:09 am

I'm noticing that about every 2 weeks I need to put in quite a bit of air in my rear tire. It get's down to about 15psi in that time frame.

Anyone else see this? Should I take it in and have a tech search for a leak?

This is probably why my mileage is so low

r1150rr · Post by **r1150rr** » Thu Nov 16, 2006 10:20 am

That sounds like a leak to me. I would have it fixed asap.

Post by **baltm604** » Thu Nov 16, 2006 11:47 am

Here is what you can do to test:

Get a spray bottle (old windex bottle or something similar) and fill it with water and a little dish soap.

Put the bike on it's center stand, make sure it is in neutral, fill the tire up to pressure (40psi or so).

now spray the tire, the bead along the rim, and also spray the valve stem.

Look for the bubbles, there is the leak!

If you find a nail or screw in the middle of the tire, you may want to try to plug it.

NOW: I DO NOT WANT TO DISCUSS THE VIRTUES OR RISKS OF RIDING ON A PLUG TIRE, THIS HAS BEEN COVERED MANY TIMES BEFORE!!!!

What I am suggesting is that at some point, you will be stuck somewhere and have to use the plug kit that came with the bike, or one you purchased after the fact. Either way, this could be a good time for you to practice and see what it is like, so when you really have to do it in the dark in the middle of nowhere, it will be a familiar process.

Good Luck,
Bill

Post by **challey** » Thu Nov 16, 2006 12:05 pm

A 20-25 PSI loss over 2 weeks is well beyond the normal leakage rate. I'd check the easy things first - carefully look over the tire to see if something has punctured the carcass. I once had a small brad the punctured a car tire making a very slow leak. Next check the valve and valve stem with some soapy water.

If the leak is from the valve or stem, you should be able to easily replace the leaking item. If it's a clean puncture (nail or screw) in the tread area, you may be able to repair and resuse. You'll hear lots of opinions on this (and I am the first to say that the only 100% safe repair is a new tire) but a carefully applied radial tire patch, where the tire is removed and the puncture patched from the inside, is probably a 99.9% safe solution. Just remember that this opinion is worth every penny you paid for it.

Sit · Post by **Sit** » Thu Nov 16, 2006 10:34 pm

I would agree that is a leak.

Glad this came up though because I always hear people talking about checking the air in the tires all the time. I understand the reason for this, like in your case, maybe a slow leak has developed or you have picked up a nail etc. But pending neither of these, how often do tires loose air? I have metal caps on my valve stems with rubber o rings in them and I can go for two months or more and not loose a pound. I sitll check weekly if not more in case I have picked up debris or something else has failed, but pending those, my tires always seem rather good at holding air.

Post by **socalrob** » Fri Nov 17, 2006 3:42 am

Challey,

Is there an easy way to replace a valve stem? I thought you had to take the tire off the rim. I'm asking cause I was stranded recently with a badly leaking valve stem.

Post by **owldaddy** » Fri Nov 17, 2006 9:01 am

Valve stem guts can be removed with a special tool, they are easy to take out and reinstall. Takes a minute to do it. So if you find air escaping from the stem, just pull out the valve seat/spring, and replace it. The tool is cheap and can be found at most auto parts stores.
Don

Post by **ProductUser** » Fri Nov 17, 2006 9:15 am

I've recently found that my slow leak was casued by a faulty valve stem. I just replace the valve, not the stem, in about 30 seconds. Oh -- the high quality valve stem cap I used kept the air loss to a minimum.

ProductUser.

Post by **challey** » Fri Nov 17, 2006 3:31 pm

socalrob asked:

Is there an easy way to replace a valve stem?

Replacing a Schraeder valve (the guts) is very easy. You need a 2-prong tool that virtually any auto parts store has. There are also metal valve caps that have the tool built in. Just insert the tool and unscrew the valve. There is another special tool for the stem, which is a bit more difficult removal/replacement. You can do either with the tire mounted. It's more unusual for the stem to leak - it is a pretty robust piece of rubber and a snug fit on the wheel - valves themselves go bad more often. I used to carry a couple of replacement valve assys and had one of those caps with the tool built in. Was probably a good idea that I should take up again. Very low cost, low space peace of mind.