Police lawfully stopped defendant because the vehicle he was driving did not have a visible front license plate. While there are exceptions to the statute requiring vehicles to display a front plate (Wis. Stat. § 341.15), the “great majority” of vehicles on the road are required to have a front plate. Because the officer did not see one on the defendant’s truck, he was justified in stopping the defendant to investigate further. (¶¶8-9). Further, the officer’s failure to state he was aware of the exceptions to the front-plate rule does not mean he made a mistake of law that invalidated the stop under State v. Longcore, 226 Wis. 2d 1, 594 N.W.2d 412 (Ct. App. 1999); he testified he believed a front plate was required in this case and so could stop the vehicle to investigate further. (¶¶4-5, 9 n.3).