So, based on reviews that I read as well as advice from my local tire guy, I decided to get Nitto Motivo 225/50/17 tires to go with my new Volvo "Amalthea" rims...
The Motivos have a 60,000 mile tread life warranty and have a slightly higher load rating at the same 50psi than the OEM 15" Continentals had, so I didn't have to get the TPMS's re-calibrated either.
An added bonus; my speedo has been reading 2 mph too high since I bought the TC (based on data from 2 different GPS units). The first thing that I noticed yesterday after I installed the 17" tires and rims was that my speedo is now agreeing with the GPS's at all speeds.
I like the ride with the new tires too; firm and stable.