Basically they are the same tire and rims, just the design of the rim looks different. Here check it out all the 2.8 rims on this page will fit a volcano.

[link=http://www.allaboutfunhobbies.com/tireandwheelaccessories.htm]http://www.allaboutfunhobbies.com/tireandwheelaccessories.htm[/link]

And the 2.2 rims any of them will fit the redcat buggies
All the 1/8th scale rims will fit any of the redcat 1/8th scale trucks and buggies.