G'day and welcome to the forums.
How old is the MBP? If it came with say Leopard, you cannot go backwards. What of theTiger discs? If the machine is older, say 2005/2006, did the Tiger install disc come with the computer when brand new? The first five or six MBP used Tiger, from then on February 2008, Leopard was the system installed. Intel Macs use a different set of Tiger install discs to PowerPC machines.