Would like to add wider meatier tires to my truck

If your stock tire size is 275 mm wide then that means you probably have an 11 inch wide wheel. The absolute max you can go is 305 mm wide. I would personally not go wider then 295 mm because you are in danger of it not only not fitting but blowing out a bead if you do get them to seat.

No matter what you do, I would not suggest widening the tire unless the tire manufacturer says it will fit on your wheel. Some of them are hesitant at this and do not recommend putting a wider tire on a wheel.

Also, if you widen your tire you need to thick about it rubbing while turning and it is going to be harder on your steering system and suspension due to the increased drag.

Let me know if you have questions. Thanks