tires and brakes on my four winds chevy 3500 chassis

The big bolts that hold the Caliper Mounting Brackets onto the rest of the Spindle Knuckle? On Ford they're probably metric around maybe 16mm, 21mm socket. I couldn't get ours off when I replaced a caliper during a trip. Even 1/2" drive breaker bar was difficult. I have a 3/4" drive set and used a reducer to 1/2" for my socket. As I recall the torque for those is more than the wheels.