Straddle-type wheeled vehicle and frame thereof

A straddle-type three-wheeled vehicle has a frame having an upper frame member, a lower frame member, a forward cross member interconnecting a forward portion of the upper frame member with a forward portion of the lower frame member, and a rearward cross member interconnecting a rearward portion of the upper frame member with a rearward portion of the lower frame member. A strut extends diagonally from the forward cross member to the lower frame member. The vehicle has an engine mounted to the frame. An air box of the vehicle has at least a portion thereof disposed above at least a portion of the engine. A fuel tank of the vehicle is disposed rearwardly of the air box.