Time affects all things and a problem with older tractors is rust, especially with the rear tubed tire rims. If your Satoh S650G has rusted out rear wheel rims they can be replaced if your hub is still good.
We have found a replacement rear wheel rim that appears to be compatible with the S650G even though it is made for a handful of other tractors.
This rim is from Stevens Lake Parts and is a 10″x24″ rim with 4 mounting points that are 14.5″ Center to Center.