Are these wheels suitable for CLK?
 

I have a 2004 CLK with standard 16" wheels. Tyres have markings- 205/55 R16 91V.
I would like to fit 18" wheels and would like to know the spec required to keep the speedo reading correctly.
I have been offered the wheels and tyres below. Are these suitable?
Front Wheels have the following markings:-
DC 028
A221 401 1902
Austria
8.5J x 18 H2 ET43
Fitted with Brand New 255/45 18 99Y Pirelli P Zero Rosso Tyres

Rear Wheels have the following markings
1.1881
A 221 401 1502
Belgium
9.5J x 18 H2
ET43 HLB
Fitted with Brand New 275/45 18 103Y Pirelli P Zero Rosso Tyres