Must be something contagious experienced flat at 5 hours run time MT225S had tire plugged at Firestone dealer. My case it was roofing nail.I left it another 5 hours as time was permissible for the repair. Now 147 hours later on the clock tire holds air. Very happy with tractor it has been work horse. The mmm is best mower I have used 25 years nice level now.Oh thank you, I didn't really want to use slime but I couldn't remember the other way the husband use to do the flats, and I wanted to make sure it was okay to use on the tractor, so Tire Plug it is. Thank you Thank you.