My 2012 ZD331 came with 26x12R-12 turf tires. I have hilly terrain, some of which stays wet into June. As noted, turf tires do not offer good traction in these conditions. I bought a spare set of wheels and mounted Maxxis Bighorn 26x12R-12 (6 Ply) ATV tires. Bighorn tires come on some John Deere Gators, Bombardier and other high-performance ATVs and have a deep, aggressive bar-type tread. After receiving the tires, I was concerned that the extra height of the tread might not clear the fuel tanks. I mounted them today and there is barely 1/4" clearance. They also raise the rear of the mower about 2 inches. Therefore, I had to adjust the mower deck height to compensate and get the same height cut. While it seems to mow okay, the deck is not level and I need to check my manual to see if the rear of the deck can be lowered to level it. I am also concerned the more aggressive tires may put additional, undue stress on the trans-axle so I want Kubota's advice before I ruin the trannie.