v 2.01

11 September 2013 : Added old tread_type to tire_type. Renamed old
tread_type "tube" to tire_type "bike". Added tire_type "auto"
v 2.00, 10 September 2013 : Added tire_type and rim_width (from wheel)
parameters. Change values accepted for tread_type parameter. Changed
hollow_tube_thickness parameter to hollow_tire_thickness