Have replaced 2 different front tires due to small slits on the sides walls of the tires. Nothing seems to be rubbing or scratching the sides. I keep approximately 5 lbs lesser air pressure than the maximum on the sides of the tires. When done mowing I do run the zero turn in circles out on the street to get any excess dirt out of the tire treads, could this cause it? Dealer has no idea what is causing it, when I replace a tire it comes with a new trim, I am very careful not to run over anything that would hurt the blades or tires, just can not figure out the cause of 3 to 4 slices on the sidewalls.