I, for a while, used Kenda TrakMaster IIs for the rear, (110/100-18) and also a Duro All Terrian (80/100-21).. Both are like $30 each and have lasted over 3 years, still more than half tread.. and have execelent traction, the Duro has the best traction I've ever seen on the track, I don't know why.. It's a great tire. Hmm.. I've had best luck with these.
But it is also a 250.. I just really like both tread type.. Plus, then, I didn't want to put too much money into tires that wear down right away..
Hmm.. Just a thought..