In Michigan, there is a 160,000lb limit, unlike the more typical 80,000. I'm not an expert, but I believe it is up to 20,000lb per axle and up to 8 axles on the trailer. But your typical 18 wheeler set up can gross 80,000 - just like other states, you don't need a four axle van, for example. Some of the other guys on the forum may be able to elaborate on the weight limit laws.