I run 28" dirt devils now and have run 26" mudlites. I am getting a lift now and am going even bigger on my 660 grizzly. My wife runs Kenda Executioners on her 450 polaris 27x10x12 on front and 27x12x12 on the rear. We try and do alot more mud riding than fast trails.I run c-series 5's on my grizzly and she runs polaris aluminum wheels for the offset.