One of the most frequently discussed issues on the 356Talk list is wheel size. One school of thought favors 5 1/2" wheels for their ability to put more rubber on the road, while others prefer 4 1/2" wheels for their lower unsprung weight, original 165/15 tire size, and more nimble feel, especially at lower speeds. However, in the past few years, a number of 5.5" lightweight wheels have become available that are much lighter than any 4.5" wheel, negating that advantage. They are the "MgTEK" or "TECNO-Mg" wheel, a reproduction of the original "Tecnomagnesio" magnesium alloy wheel that for a time was sold by NLA, and aluminum billet wheels sold by West Coast Haus. (As of May 2008 neither of these wheel types were in production, but as of August 2010 a new version of the classic Tecnomagnesio is being sold out of Italy.)
– Barry Brisco