For the covers, try eb@y. There are plenty there. I have also seen some that will customize the cover for you.
I believe that the tire size is going to be either 21 or 32 inches depending on the package your dad got.
2007 Sahara Unlimited
4x4, Auto, Jeep Green, Tow Package, Soft top, 3 inch spring lift, MBRP Catback