They will fit, but it depends on what you are going for. I assume these are for the fronts of you CP. I would get at least a 6" wide rim, alot of guys run those. I run a 7.25" rim on mine to spread out the sidewalls of the tire so they don't flex so much, alot of guys run them this way too. It all depends on what you are looking for out of your tire. Personally, I'd wouldn't run any smaller that what I have, even that spread out the tire still flexes on hard pack tracks, I have to watch my pressures very close.
Hope this helps
Paul