Is it possible to squeeze a wider tyre on the rear? Or fit buell rims to it? 

Hi , you could portably squeeze a 160 in the rear but it's only a 3" rim so not advisable pluswowing 3" lower the larger profile would rub on the inside of the guard Easier and then there's tyre to belt clearance to think about as wel , buell rim would probably need a wider swing arm then you still have off set the front pulley to line the belt . Let us know if you try

Just had a closer look at mine , you could probably fit a 180 or 190 in the stock swing arm . So buell rim would not be that hard to fit

Got heavy duty in springwood looking into it for me. 200 kit its been done here in oz search on you tube for wide tyre kit for iron looks neat so im going for 1200 kit as well