Front axle weight

Neither. It's according to your tires and axle rating. For all practical purposes, whichever is rated less would be the limit.

 

12000 is a rule of thumb. Open your atlas and see what the states you are driving through state for max, as there are several requirements. Now look at the rating on your tires. Last look at axle weights usally on the door jam.
Front axle weight is the lesser of the three.

-Steven

 

Generally 12,000.
My 5th wheel is set to give a steer weight of around 12,300 with full tanks and a full load. It has never been an issue.

 

Clyde07 has the correct answer.

People always think it is 12,000 because if you have 34,000 on the drives and 34,000 on the trailer tandems that leave 12,000 on the steers to get to 80,000 but you are actually limited by your tire and axle ratings, whichever is less.

 

I run with 12,800-13,300 depending on fuel load regularly across scales all over the nation and have no issues. (Freightliner Cascadia) This gives you some lee-way on your other sets.

 

My heavy hauls front axle are rated at 20k with a limit of 18k because of the tires.