The heaviest IRT motor cars were created when the some of the l904 Gibbs were converted to MUDC, creating a car that weighed 89,140 lbs or so, almost 45 tons. Before MUDC they weighed about 43 tons, a shademore tha the 1907 Deckroofs. The Standard body or Hedley cars ran from almost 39 to almost 41 tons, I do have exact weights if you want them, dpending on High V or Low V, MUDC or not, etc. Trailers ran about 28 tons. 7 motors, 3 trailers the norm, all cars 51 feet.Even though the BMT standards were lighter than the D types they didn't come in that much heavier than the IRT stuff size for size.BTW my shop friend and IRT guru of my youth advised me that the old IRT motor truck alone weighed 12 tons....6 for the truck and 3 for each motor, they looked almost the same as the diesel loco motors. Guess they pack a lot more power into the same space now.