Abstract: A vehicle frame includes a plurality of hollow tubular members welded together. An opening in a side wall of the frame which receives a door or window of the vehicle is bordered by at least two hollow tubular members which are interconnected by a non-tubular, reinforcing corner member. The reinforcing corner member includes a pair of solid parallel plates spaced apart by a perpendicular cross-member. Each plate of the reinforcing corner member has integral first and second elongated portions extending on either side of a continuous curve therebetween which has a substantially constant radius of curvature such as to define a smooth transition between the integral first and second elongated portions of the plate. The reinforcing corner member distributes stress away from the curved corner and to the tubular members, thereby preventing stress concentration at a joint between the two tubular members surrounding the opening in the frame.