Hi CharlesR,
Welcome to the Heartland Owners Forum.
The load range G tires of choice are the Goodyear G614 and the Sailun S637. Both have good reputations. The Sailuns cost quite a bit less and are pretty widely used now.
But, you must ensure that your rims are rated for 110 psi / 3750 lbs. You can check for a stamp in the metal on the inside of the rim.