I have used and sold FlatFree for several years. I believe it is probably similar to Slime. From a sales side, it is hard to get some people to think about prevention.
Here is my complete take on it:
1. Make sure your tires are balanced before putting it in. If they are balanced, they will be better, if not, they will be worse.
2. It works best in tubeless tires, since it forms a plug as it moves.
3. It really does seal. I've had 1/4 inch bolts in tires til the head wore off and the bolt was pushed through. There are a few pics on my site.
4. It cannot seal 1 inch tears, although I've had it hold the tire up for several 10 miles or so in those conditions. The centrifigal force and the liquid combines well until it is gone or you stop.
5. When you have multiple punctures over the life of the tire, eventually it will need topping off.
6. When you pull a nail or bolt out of the tire, be where you can immediately drive fast a few miles to reseal the tire without the bolt.
7. If you don't have a dryer on your air hose, and you have various punctures requiring the addition of slight amounts of air over the life of the tire, eventually it will become diluted with the water from the air hose and thin out.
8. It is outstanding for ag equipment and off road equipment.
9. I do not like to put it in real wide, low profile tires. The internal ribs sometimes keep it from spreading properly and maintaining balance.
10. If you do get a large hole that you need to patch, do not use water soluble "cold" patches. They will fall off.
11. If you have an alignment or other problem that wears the tires unevenly, unless you can find a high speed balance machine, you will have to dismount and wash out the tire before balancing. High speed balance solves this problem, but most people have low speed equipment.
12. Since it works with the centrifigal force, it is not effective for puctures at slow speeds in the last few feet before stopping. But you can then park with the hole down, inflate the tire, and drive on.
13. Before using it, I've had as many as 32 flats in a week. In the years that I've used it I normally see one or two a year.
14. A couple of years ago, I hit a riverbed right after a storm. Blew one tire and stopped immediately. Two others were leaking. I put the spare where the blown tire was (3 inch rip), put the puncture downward in one and inflated it, then the other leaking one downward and inflated it. Jumped in and continued the journey 150 miles through the mountains to my destination. Saved me hours of waiting for someone to pass or help.
