problem with tire loosing air in cold weather

[Carroll_B]

I have a 79 C-20.  I put radial tires (9.5 X 16.5) on the original rims.  In warm weather I have to add air to one tire about every 5 weeks.  When the temps drop to 40° I have to add air about every week to this one tire.  When the temps drop below freezing the tire will go flat in one day.  Do you think I have a tire problem or a rim problem?  I only drive this truck about 3 days a month

[chevy4x4trucks]

Well, the easist way I can think of to check is have two of the tires swapped.  If the problem is w/ the tire it'll happen on a different rim, if the problem is with the rim it'll happen w/ the different tire.

 

For 20 bucks it's an easy way to figure out the problem.

[RyanbabZ71]

what kinda rims are they? (steel, aluminum?)

 

I know in my owners manual it states tires on aluminum rims will loose air pressure during colder months.

[TDS 854X4]

I have encountered corrosion on the inside of the rim, where the tire bead sits.  This can grow rough enough to allow air to leak.  Corrision comes from the moisture in the compressed air that you get most places.  Any tire shop can check this out for you by un-mounting (dismounting?) (whatever the technical term is) your tire in question and giving it a look.  Often just a light sanding will smooth out the inside of teh rim enough.

 

As mentioned, aluminum rims are more succeptible to the cold-weather leakage than steel are, not knowing which wheels you have.

 

Good luck!

[Colorado Kid]

I'll bet that with a little soapy water you'll find the leak at the bead-rim interface, or where the valvestem meets the rim.

 

When I had a persistant problem like this I discoverred it was because the tire shop had mangled the bead when mounting the tire.  They wouldn't take credit for it though...claimed I'd damaged the bead by driving on it flat.  I hadn't, but how do you prove that when they already have your car on the lift?  They were astonished when I mounted the spare, threw the damged tire and bare wheel in the back and left.  Bought a tire at another dealer down the road...who felt bad for me when I told the story and gave me the tire at cost (less than 50% of advertised "sale" price) and didn't charge me to mount or balance it.  

 

Who do you think I buy tires from now?  That's right, and so do my parents and my in-laws and a few other folks I know....

[Carroll_B]

Thanks for some good ideas.  The rims are steel so rust at the beading could be a problem.  I'll try the soap around the bead.  If memory serves me I had them dismount this tire about 4 years ago and they found nothing wrong.  This week the weather has been just above freezing so it took about 8 days to go flat.

[Carroll_B]

Found the problem.  These rims have valve stems that are metal and have a nut that holds them in place.  I was going to put air in the two tires that were low and take it to a local tire shop.  I noticed that the valve stem didn't seem tight.  I tighten the nuts on the stem about two turns and now the tires will hold air for 6-9 weeks even with the temps below freezing.  Can't believe I didn't check this before.  Guess the cold weather would shrink the rubber seal on the inside of the stem and allow the leak.  Thanks for all the suggestions.