I just pulled the floor out of one section of a Gorilla shelf unit (or whatever Sam's is calling them nowadays). The Gladiator shelves are pretty much the same thing but thicker, if you want to see one online.
I can still use the other shelves in/around that unit. Obviously I have the shelves double-stacked in there, but I have more than an average amount of spare/alternate parts and **** in there.
Depends on whether or not you have one of those, or have space for one, and whether or not you need every last shelf they come with installed for storage. If not, pull the floor off one shelf and drop your tires in.
They're around $150 or so.
Forgive the lighting. I was using a $30 point and shoot with the built-in flash in a dark room, as the ceiling lights were out and I didn't have a ladder tall enough to swap them. It looks a fair bit nicer in there in person. I might have brightened the shot up in photoshop.
Don't even remember when I took this, actually.