To add to Birds post the "slime" type product is not fix a flat which is only good for that particular leak and, as Bird said, also uses a propellent of propane, hence the danger. To answer Westbilly the answer is 1. a tractor tire doesn't need to be balanced due to the low speeds and the product stays liquid and so self disperses evenly around the tire as you drive. Even though the balance isn't a factor for tractors it would be for cars. Since this product is designed to be put in car tires too I suspect the balance issue isn't. The main reason I like it is it not only fixes that leak it also fixes future leaks. Putting it in took about 5 minutes per tire if you use the pump it comes with (like a ketchup pump with a plastic tube on the end that goes over the valve stem). Just take the valve stem out, wait for the air to stop coming out and start pumping in. The stuff from gemplers looks like pepto bismal with a little thicker consistency.