New kiteskater lvtdave just came up with a great source for off-road wheels. If you are making your own kiteskates, this site should give you some good ideas. They sell direct to the public and offer 12" wheels (like I use) and 14" for those who want a smoother ride.
http://www.skywaytuffwheels.com

Building your own skates? This will help:
http://www.doomwheels.com/articles/buildwod.php

BC

Dave

Which product do I look for?

Is it the tuff wheels?

Check out the 12.5 inch Tuffwheels:
http://www.skywaytuffwheels.com/2002/products_003.htm