Metric wheels

["John Hertzman" <johnhertzman@domain.elided>]

Responding to Michael's "If there are other metric wheels out there I'd like
to know" Greg mentioned the 165-400 tires of the 2600.



The Alfas (and A.L.F.A.s) of the first decade and a half wore 820 x 120, 860 x
160, 820 x 135, 800 x 130, 775 x 145, and 880 x 160 tires, the last on the P1.



Whether coincidence or not the switch to inch-designated sizes seems to have
coincided with Jano's coming to Alfa from Fiat; 19 x 5.25 and 19 x 6 tires on
the P2, 28 x 4.95, 30 x 5.25, 27 x 4.75 on various versions of the 1500.



As far as I know all later Alfas up to the 1900 had inch-designated tire
sizes; the 1900 (and 2000) wore 165 x 400. The Giulietta introduced the
current hybrid designation, 155 x 15, metric sections on nominal inch
diameters. I believe, but don't know, that some of the wheel dimensions were
very nominal, with identical rim sections under both measurement systems
rounded off to neat whole numbers; from around 1955 I believe I remember
Pirelli 155-15s and Michelin 155-380s being interchangeable. I also have an
impression that the French (being French) used metric system designations more
persistently than other metric-system nations. What part the early technical
dominance of the British (Dunlop being the original pneus, Rudge-Whitworth
being the original removable wire wheel system) and/or the early commercial
dominance of American industry played in all this I cannot say, but I don't
see a better reason for things like Alfa switching from 165-400 on the 1900 to
6.00-16 on the 1900-based Disco Volante.

Cheers

John H.
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