Not legal in my state ... ALL semis are required to stay out of the left lane on multi lane interstates, except to pass if that really ever happens.
^ I know of no 4 lane interstate highways [a 4 lane Interstate highway is a multi lane highway] that has a restricted lane, though ICBW.
I drove 540 miles yesterday from Greensboro, NC to Fredericksburg, Va and back. I noted truck restricted lanes during the trip. I merged onto I-40 in Greensboro beginning the trip, going East through Greensboro...no lane restrictions and a 60 mph zone. Just East of Greensboro before Burlington, NC 2 left lanes restricted to Hillsborough, NC where restrictions ended and I merged onto I-85 North. No lane restrictions on I-85 North to Petersburg, Va, roughly 120 miles. Merged onto I-95 at Petersburg, Va at mile marker 52 going North on I-95. No lane restrictions around Petersburg and through Richmond until MM 84, a distance of 32 miles. From MM 84 to MM 118 2 left lanes restricted, a distance of 34 miles. The vast majority of the trip were on Interstate highways with NO lane restrictions. I saw NO trucks using restricted lanes during the trip. It does happen and I've seen it many times, but the vast majority of truck drivers are safe and courteous but the ones who aren't always stand out, just like everything else in life. [I didn't go to school to learn how to drive a truck, and my last traffic citation was in 1985].