I doubt it's any bigger if even as big as a greyhound bus, and is still smaller than articulated buses and B-trains. But to answer your question, yes there is a limit; width no more than 10ft, the only real exception to that would be trucks hauling wide loads, and there are some requirements for trucks like that such as having amber emergency lights signs clearly displaying wide load and 2 chase trucks one front and one back. As far as length it depends on the road and basically comes down to can it actually drive on that road reasonabley safely, for example B-trains (a tractor with 2 trailers) are legal, but i doubt you will ever see one driving in the suburbs.