I have before. It's a little tough to negotiate on the prices if you're just buying tires alone (i.e. you're going to change them yourself). If you're going to have them mounted, balanced, stems, etc then getting some money off is a little easier. Sometimes there's not a lot of wiggle room on the tire price, but sometimes there's room on the mount and balance fees. I've had luck with pulling the manager aside, away from the crowd, and working out deals. They seems to be more willing to make a deal when it's hush hush than in front of everyone else. Helps prevent the, "Hey I want the same deal!" situations. Helps if you use the same dealer and location for all of your tire needs.