RE: Traxxas
You probably won't find any tires in current production that will fit.
But I did find this site which shows a Cat w/ 2.2" wheels. [link=http://www.ultimatetraxxas.com/projects/cool-cat/]http://www.ultimatetraxxas.com/projects/cool-cat/[/link]
He used HPI Super Star wheels with Tamiya Frog Re-Re hex Adapters for the rear.