I used to ride a 1992 Peugeot mountain bike, been riding it for 15 years. Never had a flat. Never changed the tires. Never changed the tubes. Never changed ANYTHING on that bike. It still kept going until it died. Now it sits in the rain gathering rust. But I only stopped riding it coz the rear tire blew. Then I bought a new bike.

(Just kidding, had the next bike about a year before the rear tire on the old bike blew).