Started saving some of these weights off of vibratory equipment at work. The average 16-18 pounds. I can get 10 in a 16” span which will give me around 170-175 pounds. 10 will work great on the front and I’ll probably make up a heavy hitch that will hold two rows on the back giving me close to 350 pounds. The centre hole where they mount to the shaft is 1 3/8” that’s probably how I’ll mount them and I can tighten the bolts down keep them lined up and not rattling. They measure 6” high and 9” across and about an 1 1/2” wide.