rotate and/or replace the tires every spring and put in my spare tubes. Carefully inspect the inside of each tire for any thorn, wire or fragment that might have worked its way in. Also carry the spare in a plastic bag - it is easier than keeping it in the original box and protects it from road grit. That would be an interesting marketing idea for tube/tire companies - package their tubes in a sealed pouch. I get new spare tubes in the spring.
Think of the project as my annual homage to the flat fairy - who has been very very nice to me. Tx FF.