Steel Offset

wheel size plus offset and backspacing in the theft of alloy wheels steel wheels beetle?
Tire Deal for my Beetle, but I am aware of the dimension of the compensation to backtrack. Said steel wheels 16 x 6.5 and 42 and I 16 x 6.5 alloy and 42, but allow the change or backspacing is the same between the two?
Backspace is the distance between the inner edge wheel inside the wheel. Offset is the distance between inside the wheel and the center of the wheel. So if the offset and width of wheels the same, the decrease is the same. Where appropriate, all measures appear to be the same.