I was going to give up trying to find a source for the tires I used on my Long Tom...........and by pure dumb luck I found this source. The size is perfect, and the commercial tread pattern is actually seen in some photos of the actual artillery piece in WWII. The rig uses 10 tires.

http://www.hobbyking.com/hobbyking/s...2pcs_Set_.html

Rex

http://www.flickr.com/photos/13963542@N08/4343075320/