Utah Trikes produces lots of good videos. Here is one about various available options one can pursue to avoid getting flat tires. I noticed that the very first option mentioned is my choice … Schwalbe Marathon Plus tires. It is still the best tire money can buy and most sensible approach to the matter of avoiding flats. You not only get excellent flat protection but you get incredible wear. … 2 to 3 times as much as the Tannus. It is a lot of tire for the money. I personally am very unimpressed with the Tannus tire.
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Tadpole Rider 
Schwalbe Marsthon plus is the only way to go. Period. I just replaced the schwalbe Duranos on my Catrike 700 with them. I went through two sets of Duranos in 5000 miles of paved trail riding and the Marathon plus is much more comfortable, never will get a flat and sidewalls are much stronger. I am anticipating 10,000 miles on them. I’ve gotten over 9000 miles on my Catrike 559 with marathon plus and they have plenty left. Haven’t had a single flat since I replaced the original plain marathons with them. Great value, reliability and comfort. Take it from a guy riding 10,000 miles per year!