Wheels on the Fire Truck Go Round and Round

I guess Bryson is bored with the “wheels on the bus” song, which used to be his favorite. He interrupted me just as I was getting started:
Bryson: engine, engine!
Me: The engine on the bus goes rummm rummm rummm….
(He really likes engine noises, go figure.)
Bryson: Fire truck song, fire truck song.
(I don’t think I know a song about fire trucks, so I fake it)
Me: The wheels on the fire truck go round and round….
(It doesn’t sound right, but Bryson liked it enough that he was singing it to himself after I finished)