I run these rears also (but use 205/55 front) and have two issues that might be important to you.
1. 245/45 16 inch seems to be a VERY hard size to locate. I had a tough time getting replacement tires.
2. the 9" rear wheel that I had on my car was a 70 mm offset that set the tires inboard too much. I had to install a 27 mm spacer to push them out. This may have been a unique thing with my car and the PO but I was lead to believe that the 9x16 inch tires were from a 911 not a 968. I don't think that 968s came with this wheel size as an option. Be sure to check your offset.