Proof is in the puncture, Mr. Paris-Roubaix.

We have all endured flat tires. I started with tubulars, and although I haven't raced in years, now ride with clinchers. I never did like repairing tubulars because it was so laborious. For a time I did repair them but I gradually threw them out and used brand new sew-ups for my under the saddle spare. A costly venture when tubulars cost more than clinchers.
Paris-Roubaix is the Queen of the Classics, and due to the cobblestones, ruts, and danger spots that lie in wait for the oncoming riders provide the dramatic backdrop for punctures. Most get them... without it martyrdom into Hell is not achieved. Manufacturers, Michelin and Continental developed better tires for the Hell of the North. They believed tires should be inflated less than normal. And tested 250 types of tires in 5 different weather conditions to get the perfect pressure. Four time record holder, Roger De Vlaeminck knew how to avoid them with his unparallel skill over the pavé. Mr. Paris-Roubaix was particularly adept at bike handling acquired in cyclo-cross races, and together with a heavy dose of cleverness, he floated over the cobbles. With the advice of tire experts, he purposely underinflated his tires with a pressure of 65 psi down from the typical 100 psi. Better for the tires not to get caught between the cobblestones thus reducing the risk of punctures. "Everytime I won Paris-Roubaix, I never flatted," said De Vlaeminck. Years ago, riders carried spare tires over their shoulders and much to their dismay repaired their own flats. Changing flat tires with cold, wet and frozen fingers upped the added stress level to the demoralize rider. It only added to the spectacle and made this race into an enduring spring classic. By 1965 organizers sanctioned wheel changes between team-mates, the allowance of team cars and motorcycles with spare wheels to follow close to the action. Early racers used bamboo front rims for it's resiliency. Also, hanging tires in the garage to dry out was another way to make them resistant to punctures.

Although, tubulars had a significant history in bicycle racing, clinchers had a small but prominent role. In 1997, little known Frenchman, Frédéric Guesdon of the France de Jeux Team, won Paris-Roubiax on clinchers. He outsprinted Belgium strongmen, Eddy Planckaert and 3 time winner, Johan Museeuw. Guesdon had added help and won under the keen guidance from his team director, 2 time winner, Marc Madiot.
He may be the only rider to win Paris-Roubaix with clinchers.