Gross weight / axle weight

Bridge laws vary by state. Google "truck bridge law".

Gross depends on what your truck is licensed for. Usually 80,000. Sometimes 76,000, sometimes 105,000. It depends. Ive had trucks in each of them ranges when I was a company driver.

If you are asking about the weight limits on the trailer only took me 3 secs to google that and find this:
A three-axle tandem (tridem) typically has a maximum weight limit of 42,000 pounds when spaced 8 feet 1 inch apart, or 42,000 pounds for a 3-axle group with a minimum spacing of 3'6".

 

This is an easy to understand explanation of the federal bridge formula.

 

You’ll want to get your 5th wheel where you want it, then measure from the center of your front drive axle to the center of the rear trailer axle. Once you know the limit for that 6 axle inner bridge add your steer axle weight to that and that will be your max gross.

Also make sure you check Oregon’s bridge chart as that will probably be lighter than every other state up there. Example: with the 8 axle setups I drove I was good for 104,500 everywhere except I could only go 101,500 in Oregon.