Abstract: A generally tubular vehicle frame assembly includes a tunnel, an engine support, a forward support assembly, a suspension arm pivot base assembly, and a rear brace assembly. The forward support assembly, suspension arm pivot base assembly, and engine support generally form a triangular shape as viewed from the side. The tubular construction of the frame assembly enables the same forward support assembly, suspension arm pivot base assembly, suspension system, and steering system to be used with variously sized tunnels by switching just several tubular components of the frame assembly. Left and right lower suspension arms are pivotally connected to the suspension arm pivot base assembly for independent pivotal movement relative to the frame assembly about a common pivotal axis. The left and right lower suspension arms being constructed such that the same suspension arm can be used on either the right side or the left side of the vehicle without modifying the pivot point of the ski.