Hi ..
a rim leak on a seldom used  tire like that is not terribly unusual.

what I do is deflate it ..
the 'lower level' is to deflate it, try to clean out around the rim some,
blow it back  up quite hard ..
higher pressure than usual, say 40 psi, then check for rim leaks with soapy
water .

if that doesn't do it ..
I might use something to help the tire slip into place on the rim as it's
being inflated better..
liquid dish soap could work there. sometimes I use wd-40 a little.

if that first level doesn't work, then I'll break it down off the rim ..
using the van's jack and the van ...be careful though.

then when it's nicely broken down off the rim, clean everywhere ..
smooth out rust with light sand paper, maybe treat rust ..
and blow it up again .
the main idea being to get to take a new clean fresh seal against the rim.
check again  with soapy water for tiny air bubbles.

----- Original Message -----
From: "Michael A. Radtke" <wa7zpu@CISAZ.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, September 13, 2010 6:48 PM
Subject: Spare Tire Goes Flat

> Hello,
>
> I was filling and checking my tires today and I was surprised to find
> the spare flat.
>
> My spare is at least 10 years old, and is in excellent shape since it
> has been off the road and out of the UV all this time.  It became a
> spare as a lightly used tire and I've never needed it.  When I did a
> quick check for what could be leaking, I found that the bead to steel
> rim seal was leaking in a lot of spots.
>
> So, what caused this problem?  All the leaks are on the side that was
> up.  My first thought was rust, but I live in Phoenix and we get little
> rain.  Besides, the rim doesn't look rusty.  Do other Vanagon owners see
> the same problem with old spares?
>
> How do I fix the tire?  I am uncomfortable with just remounting it if I
> don't know what the cause was.  I could put a radial tube in it.  This
> is a spare.  I just need it to work in an emergency for a relatively
> short distance.
>
> Information and advice please?
>
> Thanks,
> Mike   '84 GL since new --- Phoenix, AZ