I think you should the RGRs like GP20. Those are hot
As far as tires go, in addition to worrying about understeer with the tire width...keep in mind ride height as well. Cuz with 275/30 tire your tire is going to be thicker than a 265/30 tire. I'd recommend trying to keep your ride hight as close to stock as possible so you don't have to worry guage readings rubbing and other issues that come with change your tire diameter