What is the largest tire that would fit without any issues? I would really just like a little larger than stock if possible....

 

you can any size tire on all the sportsmans since same set up w/ some alterations. i have 26" on our 450 w/out any problems. just wouldnt go any bigger w/out power loss and reclutching. its the front tire width that you want to keep stock for no side rubbing issuses. just my .02

 

I have 27" ITP Mudlite XTR Mud Lites and 14" C-7 Rims on my SP450, great tires but yes you have to re-clutch or deal with some power loss.