Modified wheels

A place I work at have some large jigs for painting on, 3m long near 2m high + wide on 4 steel castors. They get filled with painted items and pushed in and out of the ovens. Doing this means they pick up paint on the wheels which breaks off randomly meaning square wheels that rattle the jigs and the items that were just painted can fall off
soooo
My idea is to make the wheels pointed in the middle so the paint can be pushed out sideways when hot and soft and the higher pressure on the centre ridge should break the paint off when cold and hard
First job was to mount the wheels in the lathe. I made a mandrel out of some steel bar, turned the end down so the wheel slide on but leaving it over hanging, a 12mm thread was put in the end, aftera 10mm stripped to easy as it wouldn't hold tight enough. The wheel was then put on and bolted up using suitable spacers.