3,500 lb. Standard Spring Trailer Axle (61" Hub Face, 5-4.5" Bolt Circle) 3,500 lb Capacity, 5-4.5" Bolt Circle (2 5/8" center stud to center stud) Axle seats will come loose with axle and are required to be welded onto axle. 2 3/8" diameter x 3/16" nominal wall round tubing. Lubrication: Grease