I think it's 16 not 100%, will check tommorrow tho, why don't you get a full sized used matching wheel and tyre, that's what I did, removed the inner tray & pump & fits perfectly. At least if you ever do have a puncture you're not limited by low speeds as you would with a space saver and can get the puncture repaired when you can, rather than straight away. It'll be cheaper than spacesaver as well, around £50-£60