There are conversion charts you can google for; that is what I used. Alternatively you can go to a dealership and they can probably tell you. You can order them online and save a few bucks, or get them locally if you're impatient.
I mounted and balanced my own tires and found it to be fairly easy. If you're planning to do the same make sure you use a rim protector (i made some out of an oil container). There are lots of how to videos on youtube. The rear is easy, but the front is much easier to pinch a tube.