The front is not a 4-3 offset. It is 5-1 so a 9" wide tire won't fit without spacers or aftermarket wheels but it does have the more common 4/156mm bolt pattern. The rear is a 10" with a 4/4" bolt pattern. The front wheel is 12" while the rear is 10" which limits your tire options. If you want to go to a 12" wheel on the rear there are a couple options. You can get a set of hubs from a 2004 Predator then add a 2.5" spacer and newer wheels. Second is to make or buy the adapters for the rear and get a set of newer wheels. Lastly I think you can still get a set of 12" wheels with the 4/4 bolt pattern from Delta.
I made the adapters for my MOSE unit because I know a machinist who was bored, and put on 12" wheels. I did go to a 25" tall tire, but I wouldn't go more than that. First, I am not sure they will fit under the machine and second, it's only a 325cc machine. So I didn't want to add the extra weight.
I picked up a set of Sedona Coyote tires that come in 25x8 and 25x10 sizes. There are other brands that would work too a suppose but the Coyote was cheap enough and the tread is suited to my needs for this machine.
Mine: 2018 Sportsman 850SP - 26" Bear Claw HTRs on OEM steel wheels(I really don't like the Aluminum ones)
Polaris Hand warmers, Mirrors.
Hers: 2019 Sportsman 450. 26" Bear Claw HTRs on Moose 427X Wheels.
2007 Sportsman 500 EFI, Polaris Winch, 25" Bear Claws QSC Clutch Kit, Hand Warmers
2001 Magnum 325 MOSE 12" rear wheel conversion. 25" Sedona Coyote tires
2017 Polaris Ranger 1000XP - Roof and front glass
2018 Kawasaki KLR650
2001 Magnum 325 Warn winch and Moose 60" plow-Sent to Daughter and Son-In-Law since his blew up
SOLD 2004 Sportsman 600 Twin