A method of threading a metal substrate on a rolling mill comprising: receiving a coil of the metal substrate; uncoiling the metal substrate from the coil; and guiding the metal substrate to a work stand of the rolling mill with a threading system, wherein guiding the metal substrate to the work stand comprises: guiding the metal substrate to a threading carriage of the threading system; gripping the metal substrate with the threading carriage; and moving the threading carriage towards the work stand, wherein the threading carriage comprises a pair of gripping rolls, and wherein gripping the metal substrate with the threading carriage comprises directing the metal substrate between the pair of gripping rolls and gripping the metal substrate with the gripping rolls, wherein the pair of gripping rolls grip the metal substrate at a position that is offset from a leading edge of the metal substrate such that when the leading edge is fed into a roll gap of the work stand, the threading carriage is spaced apart from work rolls of the work stand, characterized in that the method further comprises adding stiffness to the metal substrate by adding a diameter profile along a length of the gripping rolls such that the metal substrate comprises at least one lateral curvature across a width of the metal substrate. receiving a coil of the metal substrate; uncoiling the metal substrate from the coil; and guiding the metal substrate to a work stand of the rolling mill with a threading system, wherein guiding the metal substrate to the work stand comprises: guiding the metal substrate to a threading carriage of the threading system; gripping the metal substrate with the threading carriage; and moving the threading carriage towards the work stand, wherein the threading carriage comprises a pair of gripping rolls, and wherein gripping the metal substrate with the threading carriage comprises directing the metal substrate between the pair of gripping rolls and gripping the metal substrate with the gripping rolls, wherein the pair of gripping rolls grip the metal substrate at a position that is offset from a leading edge of the metal substrate such that when the leading edge is fed into a roll gap of the work stand, the threading carriage is spaced apart from work rolls of the work stand, characterized in that the method further comprises adding stiffness to the metal substrate by adding a diameter profile along a length of the gripping rolls such that the metal substrate comprises at least one lateral curvature across a width of the metal substrate. guiding the metal substrate to a threading carriage of the threading system; gripping the metal substrate with the threading carriage; and moving the threading carriage towards the work stand, wherein the threading carriage comprises a pair of gripping rolls, and wherein gripping the metal substrate with the threading carriage comprises directing the metal substrate between the pair of gripping rolls and gripping the metal substrate with the gripping rolls, wherein the pair of gripping rolls grip the metal substrate at a position that is offset from a leading edge of the metal substrate such that when the leading edge is fed into a roll gap of the work stand, the threading carriage is spaced apart from work rolls of the work stand, characterized in that the method further comprises adding stiffness to the metal substrate by adding a diameter profile along a length of the gripping rolls such that the metal substrate comprises at least one lateral curvature across a width of the metal substrate.