Does anyone know what size the wheels are on a Oneway Bowl Steady? I have one and would like to replace the wheels which are wearing. Oneway wants $10 each for the wheels and I see rollerblade wheels on Amazon for anywhere from $25- up for 8 wheels. I'm concerned about 2 things... the hardness rating and the bearing size. I don't know how important the hardness rating is... I guess I don't want something that is going to dent the bowl or something that is going to wear out too fast. Most bearings I see are ABEC9 which doesn't mean a lot to me... anyone ever replaced the wheels on this bowl steady and could help me with the ones I would need.... thanks