The third (back) wheel on my walker keeps going flat on me several times each season. Its always a thorn (twice), screw/nail, all types of fun stuff. My question is does this tire slime really work? Anything negitive about it? I'm thinking of adding it to all my mower tires, and my wheel barrows. Does it add a noticable ammount, if any, of weight to the machine? Just keep plugging the tires or is this stuff really as good as they make it sound?