Volvo Experts: Is There Another Way?

update:  Looks like taking a wheel off is the best (only?) way. 

My 2012 XC70 needs brakes. I’m trying to order them online and found that there are three choices with no obvious way to know which one I need. 336, 316, or 300mm diameter?

I mean, I could obviously MEASURE my current brakes, but I’m not sure I can do that accurately without taking the wheel off, which I don’t really want to do because I don’t like lifting my car with the jack I have. I ordered a new, bigger jack from Harbor Freight, but it’s been nearly 3 weeks and it says Order Pending.

The obvious answer is, suck it up and take a wheel off. But is there any other way to know which my car came with from the factory?

Signed, Captain Lazy.