I bought two
Slime tubes and one new tire. I couldn't get the exact tires I wanted. They were either out of stock or didn't have my size. So I compromised and got a
reguar Elecony mountain bike tire with 600 TPI vs 300 TPI (threads per inch) for $27. I had one tire worn pretty smooth, and I got 5 flats in one week so something had to give. I've only had this configuration a short time now, but so far no flats.
I've looked at tire inserts, tubes, liners, tires you name it. My neighbor told me he used to cut up old tubes and line his tires with those. Said it worked OK.
I'd be interested in hearing from anybody else who has any experience with these kinds of products, especially the Slime Tubes. They were only $7 apiece on Amazon.