Unless as mentioned someone changed the hub. A 1957 will be a four bolt rim be it an 8 inch or twelve. The axel or sipindel will take one inch bearings an race. You can buy these kits at most big box stores Fleet Farm, tractor Supply, or Napa in individual parts.
The rims in the add are 12inch and if they still have origianal tires T Nee used 530/12 .