Since you say you are crossing at I-190 I have to assume you are crossing at Queenston-Lewiston, not Niagara Falls. I have crossed there several times with my TT. Watch for the signs but usually they want you in the leftmost car lane, that is the one for RV's, trailers, etc. If you look you will see that at the entrance to the booths you go between square upright boxes. The left lane has extra tall ones to scan the taller vehicles. Saturday mornings are not usually too bad.
A couple of hints if you are heading there on the Q.E.W. The exit for Hwy. 405 which takes you to the border is a left exit shortly after you go over the Garden City Skyway. If you are heading back to Long Island via I-90 the exit from I-290 to I-90 is also a left exit.
