In U.S. this product in use and widely available; self-sealing tires as well (BMW, others.
Depending on where you are located, and the standard of living there, I can understand why it is difficult for you to grow your business, since this is a relatively expensive product.
You really have to determine how many cars that have owners that would be interested in this type product, and the best way to contact them.
Hope this helps, Barry