usepackage{tabularx}    %% tables with auto size
usepackage{array}   %% tables content alignment
newcolumntype{L}[1]{>{raggedrightletnewline\arraybackslashhspace{0pt}}m{#1}}
newcolumntype{C}[1]{>{centeringletnewline\arraybackslashhspace{0pt}}m{#1}}
newcolumntype{R}[1]{>{raggedleftletnewline\arraybackslashhspace{0pt}}m{#1}}

begin{document}

  begin{center}
    begin{tabularx}{textwidth}{| X | X | R{2cm} | R{2cm} |}
      Column1 & Column2 & Column3 & Column4 \ hline
      a & Some Value & This is a very long right-aligned text that should break automatically & This is a very long right-aligned text that should break automatically \ hline
      b & Some Value & Shorter right-aligned text & Shorter right-aligned text \ hline
    end{tabularx}
  end{center}

end{document}