for people wanting to use steel, look into getting it zinc coated. its not much more than paint/powder coat and is much more salt/corrosion resistant. also home depot now carries lawn wheels with tires for $40 new that use 5/8" axle.
this cart shows there size 16" x 6.5" They also carry 19" for $50...but these work more than good enough even in powder sand.
Curious on how you built your axle...did you use 2" x 2" aluminum and then weld rod on the end for the tires to slide onto? I know this is an ancient post but just trying to build a cart
