On recent trip, had driver side tire blow taking with it the bottom panel of "slide". Also had flat on curb side which destroyed rear entry step beyond repair. Unit is 2012 keystone raptor 300mp. ...
Call Keystone!!!! They should be able to sell you the J panel(maybe already painted) and fender skirt.
Any chance that these were ST tires? Internet search indicates they come with ST235/80R16E tires. Put Michelin XPS Ribs or Bridgestone Duravis R250's(cost less) on it to put tire problems behind you in the future. Both are all steel ply tires. Your story is repeated way to often.
BTW, RV.net does have a toy hauler forum area! Chris