The terrain around my home has some pretty good steeps that my FasTrak had some difficulty navigating. On those steeps, the Fastrak would often take me where it wanted to go (typically straight down the hill). It was somewhat better when the tires new, but after ~225 hours, the rubber had dried and traction was much worse. I tried the Carlisle AT101 Chevron tires and the traction and control on slopes improved significantly (especially important since my son will soon be doing the mowing).
I replaced the OEM 20X10-10 turf tires with Carlisle AT101 21x11-10 tires (the larger tires fit with no problem). In addition to increasing traction, I got a 5% increase in top speed due to the 1" larger diameter.
The part about changing out the tires that sucked was getting the old tires off the rims and installing the new tires. Not a reflection on the Carlisle tires . . . more a comment on the rim design (or just mounting small diameter mower tires in general). The inner diameter of the tire is the same size as the small diameter of the rim - actually even a little smaller when uninflated (remember the the whole tire stretches when it's inflated . . . even the bead diameter). This means that once the tire is on the rim, it's near impossible to spread it out to engage the tire bead with the rim. I brought mine to a local tire place and they wrestled with it for almost two hours. Good thing they quoted me $24 to mount them before they started. We finally used a load tie down strap to squeeze the center of the tire and managed to get it to spread enough to engage the bead allowing sufficient seal for it to inflate. PITA !
I recommend these tires to anyone with a zero turn mower that 's looking for better traction. Just don't try to mount them yourself.