With the gear ratio being fixed, I wouldn't tax/ bog the engine down with bigger tires. I bought the SUNF AO33 tires thru walmart and they have been excellent.. They are an actual 25" tire, unlike the 24 plus size that came on the machine. The tread is more pavement friendly, quiet, good mud traction, good snow traction, stiff sidewalls...can be run flat at slow speeds ! ( wont get stranded)
Price was good, very highly rated from others that have owned them.