That makes perfect sense to me whst FOG says! They are made out of spring steel and the slightest deformity can start a stress crack. My background working on aircraft causes all that to be sensible. Just like why a set of connecting rods gets polished, to remove imperfections in the finish.
Good call FOG!
This might sound crazy but operating that little tractor with a front end loader for 3 1/2 hours kicked my butt! Now I'll drive all over it for days will pack it down. Supposed to get an ice storm tonight so the moisture will help!