What
Replace tyre stem, clean the bead, re-bead the tyre.
Why
My valve was dead, it fell apart and had cracks in the rubber. But valves can be ripped out / damaged when out 4x4 so its handy to have some in your kit and know how easy they are to replace trackside. As for cleaning the bead, when driving ruts with low pressures dirt can get in there causing slow leaks. Re-beading the tyre can be a pain but a trick I saw want33's do makes it super easy.
What you'll need
In my tyre kit I now carry spare valves, valve removal tool, valve cores, wheel nuts and 'start ya bastard'
Remove wheel from car and use core removal tool to take valve core out. Then break the bead anyway you can.
- Drive over it in L4 slowly turning around the rim (how I did it)
- Strong plank of wood, edge finishing on the bead/rim junction and drive up it slowly
- Bead breaking tool of some sort - tyrepliers or R&R Beadbreaker are good
- Take to a tyre shop and have them break it
Cleaning bead use a damp rag and wipe the bead and inside of the rim, check for rust or any crap that won't wipe off and hit it with sandpaper. Run rag around anywhere you can reach inside.
Replace valve stem buy some from any auto shop. $6 got me a 2 pack.
Bob Jane wanted $10 for 1 and told me I'd need a special tool

promptly walked out.
Cut old one out from inside rim. Along the line shown is only rubber and a stanley makes quick work of it, pull it out.
Put the cap on new one to protect the thread. Using multi grips or big plyers to gently grip, ease it on through, shouldn't be too hard. If it is use some lube and/or place in warm water.
Rebeading Now the fun part.
I videoed this - youtube link. first I'll warn that I was holding the camera with my mouth so sounds a bit weird... Darth Vaderish.
Tips are, valve out or else it'll pull back off the rim. Spray of 'start ya bastard', light it up and hey presto done!
Re-inflate, use some soapy water to check bead is sealed well.
