Section 349.15 - Authority to modify weight limitations and classify highways(1) The limitations on size and weight imposed by ch. 348 are lawful throughout the state and local authorities may not alter such limitations except as otherwise provided in this chapter.(2) The county highway committee with respect to the county trunk highway system and the local authorities with respect to highways maintained by them may designate all or parts of such highways to be class "B" highways for the purpose of putting into effect the weight limitations set forth in s. 348.16, except that no portion of any such highway which is a state trunk highway or connecting highway may be so designated.(3) Any city of the first class may, with respect to the streets of such city, by ordinance increase the maximum weight limitations specified in ss. 348.15 and 348.16.