I found this discussion of the origin of track spacing fascinating. 

Early cars also adopted the prevailing wagon width to be able to run in the
ruts already on the unpaved roads. In the South, despite the use of
narrow-gauge railroads, wagon tracks were wider. Early Model Ts were sold
in the South with this wider (60 inch) tread and in the rest of the country
with the then-standard 56-inch tread. Sometimes in that era of unpaves
roads, motorists would attempt to run their cars on the rails, with or
without special wheels designed for the purpose. In the New York to Paris
race of 1908, the competitors were given permission to run on the tracks of
the Trans-Siberian Railway. On at least one occasion the American entry was
nearly hit by a train. Attempts to use the rails as a running surface being
unsuccessful, the Americans ran with one pair of wheels between the rails
and the other pair outside, considering the bumps from the ties to be
better than the bottomless gumbo of what passed for roads in Siberia.
However, the car was not at all happy with this treatment. 

The streetcars of Baltimore used a unique "Baltimore gauge" of 5 feet 4 1/2
inches (which was wider than the standard railroad gauge of 4 feet 8 1/2
inches) as required in the authorizing city ordinances that the gauge be
"the same as ordinary street carriages." Perhaps this proves that Baltimore
was a Southern city at heart. 

Don White