The OEM rim is 9" with a 3+6 offset..I wanted a thinner rim so that I could play with thinner tire sizes. The slimmer steering tire profile improves the handling greatly..
Anyway I chose 7" with 2+5 because it kept the offset profile the same and meant I didn't need to spacer to centre the rim..essentially it took an inch off each side of the rim but left the hub in the correct offset ratio and centred between the forks.
As far as the Executioners, I wouldn't do them again..my brother loves them. But for me too heavy, too rough, and too agressive..but that is why they call it experimenting. You try, you ride, you learn!
Your choice is pretty open in the 12" tires..Carlisle Badlands xtr wouldn't be a bad choice. Pick what you like the looks of..25", 26", 27" diameter, 8"-10" width is pretty safe math..have a party with it!!
For the Rocky Mountain link choose this vehicle..1986 HONDA ATC 350X and it will give you the 12x7, 2+5, 4/110 choice. Why that vehicle when that sure wasn't a stock size for it?? Who knows..site reference glitch I guess.
Current toys..
1986 Honda 350X..trail bomb!
1985 Honda 250SX..my main mudder
1985 Honda 250ES..Back in Black Trike
Current non-trike toys:
1990 Honda TRX300FW
1995 Seadoo GTX
1998 Polaris Indy Lite 340(Nearly new looking)
1998 Polaris Touring 500
1998 Club Car (electric)