I recently picked up a set of 28x9x15 goodyear slicks and put them on 15x7 wheels that I had a 9in wide street tire on and it looks too narrow. Anyone know how wide the rim should be? I have 9 in wide rims, not sure which rims to use

71 challenger convertable, 64 sport fury 383 ci with factory air 99 sebring convertable 89 CTD pup