May depend on the tyre, eg michelin xwx 205/ 70 r15 recommended rim sizes 5.5 to 7.5 (taken from michelin website ).
If I remember correctly I used to have a 255 profile on a 6" rim for my buggy. Can't remember the profile... 65 maybe. ..
Hope this helps!
Bug: '68 1200 basic, masquerading as a '67 cal looker.
2276cc Rolling Resto/Street/Strip.
Owned since 1991 and absolutely, definitely, certainly, without doubt a keeper!
Bus: '72 Devon. Gone to a new home.
Buggy: '73 Tagged SWB UK Manx (number 044). Gone to a new home.