Is this what you are looking for?Wrong answer because I'm sure he's asking about the temporary 'Skinny Spare' - you know that's the thin width tire in the spare well that's got the bright yellow stripe on it, good for only 50mph (?) and everybody knows it's on!
His wheels are R17 so I expect the spare rim to be 17 inches diameter. The T125 number is the tread width which is skinny and not 235 mm. There's no space in the EOS tire well to fit a standard spare, which is why V.W supply the narrow skinny spare. My link describes what tire markings mean.