The child seat is certainly suitable for elderly tubular steel wheels. In today's aluminum wheels have often not round, but oval tubes, the child seat it does not fit. Aluminum wheels have thicker pipes, as the old tubular steel wheels in general.
Since I have realized too late, that the child seat does not fit, I broke a plastic piece during assembly. Now I can not even a return times the defective child safety seat because I have made it self-inflicted broken.