Jim,
I was in need back in 2007. I had an encounter with a traffic attenuator at the West Virginia Turnpike Toll Booths. ALWAYS use their far outside (right) lane, it is bigger than all the rest.
Anyway, you might try contacting:
RealWheels Corporation
www.realwheels.com
3940 Tannahill Drive
Gurnee, IL 60031
(800) 982-1180
My sales contact was very accomodating. His name is Bjorn Cannon, bcannon@realwheels.com
I don't know if he is still there or not but it is worth a toll free call to find out. The rubber channel is still working for me.
I also got a new piece for the tag axle hub covers from Parliament when I was in Florida. I ran into Truk while at Parliament but that is another story.