You can go just about as fat as you want up to 285/35R19 in the rear on the 9" wide rim. A 295 on the 9" is a little dicey. The front's should be limited to 235/40R18 as not to rub the control arm nuts. Yikes.

The Bridgestone Potenza RE760 is a nice tire, but I'm not sure how happy you'd be with the run-flat version. Sure can't beat the prices, tho, especially the mount/balance cost - sounds to good to be true.

Good luck with the deal.