Don,
Thanks. I would just use this for the pattern. I'll eventually make a
urethane mold and use that to mold the tires with rubber molding
compound. For the pattern, I need something that is going to be
somewhat easy to work with as I need to figure out how to cut the lugs
on the outside of the tires. I thought wood would be the way to go
initially as it would be fairly easy to carve with a chisel and knife.

Basically, I was going to turn the wood pattern down on a wood lathe to
the approximate width and height dimensions. Then I was going to hand
carve the lugs on the outside of the tire. Now I'm wondering if this
wouldn't be easier with Polymorph. Can I carve this stuff too? I just
bought a mill, so that might be an option to get the lugs carved.

Mike