Wider tires are definitely the way to go for chip seal, but watch out that you don't get a stiff tire in the process. My may complaint with wide tires is that most of them are thick and stiff. I'd look for something like a Panaracer T-Serv or, if your budget allows, a Schwalbe Marathon Supreme (not the Marathon Plus which is as thick and stiff as tires come). I haven't tried them, but if your frame will take a 700x40 tire the Schwalbe Little Big Ben might be worth a look.