My record is 13 flats in one year on the front tires of one of the farm tractors, all from thorns. If those tires were new I'd have them foam filled in a minute, irrespective of cost. I must admit, that was a bad year but every time I walked through the door of the place I have them fixed the guy used to give me all kinds of good natured grief. He even thanked me for his vacation and putting his youngest son through college. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif Now, I have a tube installed and whenever I have a flat, I Slime it. It's worked pretty well for the last couple of years. I use it both at the farm and at home. Slime makes different stuff for tubed and tubeless tires. I'm not sure what the difference is but maybe Henro's explanation is correct. Other makes say they work on both. It's the best solution I've come up with for preventing flats. Messing with those tractor tires is a chore.