Nope, you can't do that in GT4. However you can now buy the same type of rim over and over (those BBS LMs look awesome on any car )unlike GT3 and now you can buy used rims too.
Sadly (and stupidly), no. You can have one set of wheels for every type of tire your car has (Normal, racing slick, snow, and dirt). When you buy a new set of wheels, the old one goes away.