Discount-Flag-Poles.com follows engineering manufacturer wind speed specifications for the aluminum flagpole shafts. These speeds are based on wind tests and are the guidelines the manufacturers use when rating flagpole strength. Please consider this chart when planning for your new flagpole and flag size. Example: 30 ft commercial flagpoles, with a 4" base diameter can safely fly up to a 6 x 10 ft flag during 50mph wind gusts