^^^ If you don't have one of the TRD packages (Off-Road or Sport) then you most likely have the 16x7 steelies the SR5 packages came with. As for 16x8's fitting - that depends on many variables, but this is an information thread for stock wheels, not for aftermarket fitment. There are many other threads out there talking about aftermarket wheel fitment.
That being said. Any and all additional information would be greatly appreciated!