I made a new stand for the grinders with a truck wheel filled with concrete as the base. When I went to move the completed base the bottom plug of concrete fell right out of the wheel. Well to be more accurate it stuck better to the floor than to the wheel. Looked beautiful from the top, but the bottom was hollow. Oops. If I do another concrete filled wheel base I'll do it on a piece scrap plywood instead of on the shop floor. LOL.
The weight was probably still plenty, but if a little heavy is good then heavier is better. I welded a few pieces of that rebar salvaged from the washer salvage project into the span across the bottom side of the wheel and filled it with concrete with the bottom side up. A quick level and trowel and it looks good. I used a piece of granite counter top to make sure it was flat, and then when it was almost set troweled it smooth.
Now I should have a grinder stand I won't have to stand on when I am grinding.