size or load

Forgive me for what may be a stupid question re tyre size/load rating. I have a 2006 C180 Kompressor 1.8engine, and need new tyres. My current tyres I've had on the car since I got a year ago are Pirelli - back 205/55 R16 91V, front 205/55 R16 91H M+S. When I try to order tyres online though...