Probably not. Such traffic doesn't qualify as imports into the US. Road transport comes with paperwork of where stuff is going, which is checked at customs, see e.g. the TIR convention
When a truck arrives at a border customs post it need not pay import duties and taxes on goods at that time. Instead the payments are suspended. If the vehicle transits the country without delivering any goods, no taxes are due. If it fails to leave the country with all the goods, then the taxes are billed to the importer and the financial guarantee backstops the importer's obligation to pay the taxes. TIR transits are carried out in bond, i.e. the lorry must be sealed as well as bearing the carnet. The security payment system is administered by the International Road Transport Union (IRU).
There are probably more specific US and NAFTA regulations that I'm not aware of.
Of course import tariffs would increase the likelihood of smuggling, including stuff declared to be going to Canada that is illegally off-loaded and sold in the US.
Also of note in this context, the US and Mexico have been engaged in a long-running NAFTA dispute over Mexican trucking, which the US limited allegedly due to safety considerations.
Although the charter of the North American Free Trade Agreement established a
schedule that would have opened the border states of the United States to competition from
Mexican trucking companies in 1995, and all of the United States to this competition in 2000, the
full implementation of these provisions has been delayed due to concerns about the safety of
Mexican trucks and drivers. This delay has resulted in much frustration for Mexico, which, in
2009 implemented retaliatory tariffs on products imported from the United States. In March,
2011 the two countries unveiled a deal to resolve this dispute which could help ease tense
relations between the two neighbors.