What is the gross weight of a 2010 peterbilt 389 with sleeper?

First of all there are hundreds of different configurations of a 2010 389. There are six different sleepers alone. Wheelbase differences by them selves will be hundreds of pounds different. Automatic trans over manual is around 400 more. See where I'm going. To even get close to gross weight would be a blindfolded shot in the dark.

However, you asked for a gross weight, not a tare weight. Assuming it's going to be a five axle combination (three on the truck and two on the trailer), the gross for interstate travel would be 80,000 lbs. In some states, on secondary roads, a five axle unit may be allowed a gross of up to 105,000 lbs. with a permit.