Selling my truck, DO I take the tag off?

Probably not. Different owner. Different tag. He could lease the truck from you until tag expires.
I would just remove the plate and let him get a new one.
Business is business, not friendship.

 

As the owner of the truck you are liable for anything that he does in the truck. When people sue they sue the driver, carrier and truck owner.

 

Don't be dumb, take every thing off the truck. This includes the ifta sticker, the plates and any identifying stickers.

As mentioned you are responsible for the truck.

Oh and I would never sell a vehicle to a freind or family member, because many times no matter what if something goes wrong, they will expect you to help fix the problem.

 

You transfer the tag to the new truck.

 

Liability may become an issue; What if: the driver is involved in a fatality crash. You will not want anything tying you to ownership. Or like with a vehicle Registration, facilitating movement of the truck.

 

Guy I worked with sold a car to someone in town. He left the plate on it so the guy could drive the car down for insurance. Plate was never returned. Couple years later he goes to renew his license and can't because the guy he sold the car to racked up multiple photo radar/red light tickets. Imagine having to deal with that?

 

Smart.