I think they all do. They aren’t really meant for just using instead of a proper tyre but to get you to where you need to be to sort itWhat Creepy may have meant by the tyre being a few sizes too small is the width. My spare tyre and also my ex’s, who’s we had to use last year on his car, are narrower than our regular everyday ones. It’s ample for getting you to a garage to get a new one fitted, or get you home if not too far away. We travelled about 30 miles to get home because of when and where we were and then sorted the new one out the next day. There was a warning on ex’s spare that it has a limit of 50mph. I don’t know if mine has a limit
“There's no hard and fast rule about the distance you can drive on a spare tyre, but a general rule of thumb is about 50 miles at a maximum speed of 50mph. It's important to note that handling will be different with a skinny spare tyre, so you'll need to be aware of this when you're driving.”
the idea is that you should be able to replace a tyre within 50 miles I guess. Despite what Chris thinks that he’s the only person in the UK with a car with big wheels he’s not and garages stock all sorts generally