I have an old Craftsman push mower, Model is 917.377130, 6hp. It has 9 inch wheels and one has broken. I'm having a hard time finding a 9 inch wheel without spending a fortune. I can get two 8 inch wheels with metal supports for $10 each. Can I put these smaller wheels on the back without problem? The mower has self propelled, but its front wheel drive. Thanks for any help.