Growing up on a farm all of our big tractors with loaded tires had tubes like J-Mech recommended i attempted to find tubes with TR-4 valve stems to no avail. I ended up purchasing these and loading them with washer fluid:
http://www.ebay.com/itm/150952083112...%3AMEBIDX%3AIT
To get around the easier part I gently squeezed the stem with vice grips to prevent it from falling into the rim and put a piece of rubber hose over the end and filled them with washer fluid. So far they've not spun or had any issues with going soft. YMMV.