[Gun Doc]

Tensile strength is the "maximun stretching force that a material can withstand before breaking." So, a grade "8" bolt can withstand about 30,000 more pounds before breaking, or stated another way, about 125% of the torque that a grade "5" bolt can handle before breaking.

When you torque a fastener, you are stretching the fastener and applying a load to the threaded area.

Other considerations should be paid to bolt diameter and thread pitch. Also, torque values are for dry fasteners unless the specific manual calls for lubrication...Lubrication will affect the applied torque.

Gun Doc