Change from 205/50 R16 to 205/55 R16 ?

MOIN! TERWI had already mentioned it; can one change without much effort the REIFENGRÖSSE from the more expensive 205/50 R16 to the more common size 205/55 R16? in the vehicle ticket is besides the usual 185er and 195er only the 205/50 R16 87V registered! what must I do (or pay) so that I can drive the more favorable mature, or can it not? thank you for the help!