wheelbase

wheel +‎ base

wheelbase (plural wheelbases)

1. The horizontal distance between the front and rear axles of a road or rail vehicle.
   • 1937, Robert Byron, The Road to Oxiana, “Kala Nao,”

     Beneath the snow, and after we had left it behind, the road was as greasy as vaseline, as steep as a scenic railway, and often not a yard wider than the lorry’s wheelbase.

   • 1959 February, G. Freeman Allen, “Southampton—Gateway to the Ocean”, in Trains Illustrated, page 91:

     The Southern acquired them because the little Class "B4" 0-4-0 tanks were finding heavy modern rolling stock more and more of a handful, and at war's end the railway had nothing of suitable power but short wheelbase on its books to take their place on the more tortuous of the dock lines.

Also used as an adjective in combination: long-wheelbase (LWB) and short-wheelbase (SWB).

• track : the distance between the opposite wheels on a same axletree.