A couple of years ago, coming back to Toronto from Newfoundland, we approached MONTREAL from the east, along the north shore of the St. Lawrence, on Highway 138 - The King's Road.
This becomes SHERBROOKE STREET, one of the main streets crossing Montreal from east to west. It's a fascinating drive, more than an hour long.
We stayed the night at a LOBLAW ( Canada's leading grocer) location near the heart of the city, at Cavendish and St. Jacques.
If we had no trouble doing this with our 48' rig you should have no trouble with the Interstate!