A VW Beetle originally fitted 5.60-15 crossply. The standard radial equivalent to that is 155 R15 or 165 SR15. Then the later super Beetles fitted 175/70 R15 Pirelli Cinturato CN36. Currently there are a selection of white wall in these sizes, however the good news is that Michelin now make a 165 SR15 white wall XZX, which is absolutely perfect for a VW Beetle.