Did you ever get that taken care of? Worse they can do is say no. Just emphasize that "they were the last ones to tighten it." Any establishment with a sense of customer service would take care of you.
As for the morons wrecking exotics, it's unfortunate but usually it's the morons with the money to buy those cars in the first place.
Finally, I ended up getting Z-rated Falken 512's to replace my Firestone/Firehawk SZ50's; at $523 out the door it wasn't too bad. My only problem with the place was the bait and switch they tried to pull on me: "Oh sorry, the tires you ordered are out of stock, but we DO have these Yokohama-whatevers at only $50 more per tire!"