30" tires. Lots of guys run them on stock clutch. Would you get better performance with a clutch kit? Yes. I recommend Hunterworks' round rollers and belt at minimum. I personally stayed with 28" tires for fear of turf mode failure in my 18 G2. It failed anyway, so after Polaris upgraded me to a 19 transmission I went to 30" tires. Some guys run 32s on their older Generals without issue, so I guess I got the unlucky luck of the draw.