I think it's definitely the quality/price of tires that matter as well...Derek @ BestOne always treats me well as I struggle for the cheapest cheapest cheapest deal for tires that aren't sh!t. I got cheap whitewalls for the LeBaron and my Lincoln Continental, and Derek was solid from sale through implementation to servicing.
In Florida, I got new Kumho 600-treadwear tires from TireRack sent to a local installer who set us up well, and cheaply. Knowing the price for local installers right through TireRack's website is helpful. I also like the clearance sales, but even with inside help I find you have to jump on them before they get sold out very, very quickly.
Now, my CTS-V and Odyssey need tires, and I'm more inclined to get better/name-brad tires. I find that TireRack is just such a slick site from a research standpoint.