Straight truck, flatbed steering issue

[ed200152]

2004 Frightliner M2 Business class flatbed, 14 frt, 40 rear.
When the truck is empty, steering wheel is 10 degrees to right.
When loaded, depending on weight, the wheel now is up to 45 degrees to the right. With a heavy load equalized left to right the steering wheel is constant at 45 degrees. Doesn't matter if load is to left or right side. When going over gentle rises and drops at highway speed the steering wheel moves right and then left in harmony with the rises and drops.There is no drift to left or right when wheel is let go. Play is acceptable. No unusual tire wear. The front leaf springs look good, truck sits level when empty and the springs are quiet.. I know the previous driver once had a 100 mile trip with probably 20,000 on the steers.The truck is leased by my employer from Ryder. I once complained about low speed wobble and high speed vibration of the steering wheel. They checked all steering components, rotated tires and said they don't have wheel balancing equipment.
Could there be hidden damage to a leaf spring even though it shows no cracks and sits level? I don't have that much experience with straight trucks.

[vtlowbed]

it could be that the last time the truck was alligned the tech never re-aligned the steering wheel after adjusting the tow. as for the vibration, centrimatic s work wonders but low speed wobble ells me posibly a tie rod end or a bad wheel bearing.

[Marmaduke]

You could check the rear shackles on the front springs to see if they are seized. The spring won't flex properly if they are. One sign of a seized shackel is hard hitting on the bumps.

[justahobby]

Rear Axle(s) is out of alignment. That is why the heavier the load on the rear of the truck the more your steering wheel is off centre. I would take it to an alignment shop. They can check all steering components and suspension as well