Not exactly an 18-wheeler...

I've been looking for an opportunity to take a picture of one of these produce hauling trucks....

It would have been nice if I'd also gotten one from the side.

From this you can maybe see that this is a double - a trailer behind a trailer. But what I had found interesting is that they don't have duals on the trailer. Based on what I've learned about tires and wheels and axle weights, I'm thinking this is because the weight being carried is low. In addition, I think these trailers go into the fields, and with just a single tire at the end of each axle, they can go down the rows without having difficulty with the raised rows.

The tractor has the normal 10 wheels; the first trailer has just 2 (single axle in the back of the trailer) and then the second trailer has 4 wheels - so, a "16 wheeler" if anyone is counting!