Wheel Diameter

This is a nice an easy thing. The diameter is measured from the surfaces in the picture below, the diameter does not include the lip for the tyre. Sizes that fit a mk1 are 13", 14", 15", 16"…. 17" do just fit but imo do not suit it, but it's all down to personal preference.

Choosing your diameter is down to 2 things, What wheels you like as some are only made in certain size and what brake set up you have, if you have upgraded the brakes to larger ones then you will need a larger diameter wheel to fit the larger brakes inside.