Since sport-touring motorcycles are such a broad genre covering such a wide variety of weight and power output, Michelin created two Pilot Road 4 variations other than Standard.The GT model has some bias belting to increase stiffness for heavier machines, and the Trail model is for the growing number of adventure bike owners who only ride asphalt.We mounted the tires to my Triumph Sprint ST; although I admit it isn’t the quickest steering motorcycle, the ST’s handling has always been pleasant and neutral. Right off the bat, the PR4s were getting a challenge.The initial test took us through the mountains and some very twisty roads with mixed-quality asphalt, and fast and slow corners. It was also very windy, and the temperatures varied from over 90 degrees in town, to close to freezing up in the mountains where snow was still in evidence. Michelin claims that the tires will maintain optimal performance across an unprecedented 90-degree range of temperatures.Michelin’s Dual Compound Technology has new all-silica compounds, and the rear uses a hard center with medium shoulders for grip. The front tire’s compounds are one step softer, with a medium center and soft shoulders.The PR4s worked impeccably and at no point did the tires hint at letting go, even in some pretty sketchy road conditions; I had enormous confidence no matter what I encountered.The Triumph retained its stability and predictability, and turn-in was slightly improved. Plus, the PR4s absorbed bumps well and noticeably improved ride comfort.Michelin used quality assurance company DEKRA for a comparison with their competition of wet weather braking performance. Testing a Yamaha FZ1 ABS over a variety of surfaces, the PR4s stopped shorter by an average of 45 feet — the length of three Audi A3s. That could be the difference between a heart-in-the-mouth moment, and a trip to the Emergency Room.Shop RevZilla.com for the latest Michelin Pilot Road 4 GT Tires!According to DEKRA, after two million miles of testing in Europe, Pilot Road 4 lasted 20-percent longer than the PR3. So, it seems Michelin is close to reaching the Holy Trinity of sport-touring tires: stable handling, superb grip in almost all conditions, and decent longevity.For additional information on the Pilot Road 4 motorcycle tire, visit Michelin.Story from Ultimate MotorCycling magazine; for subscription services, click here.