My wife ran over a large rock and killed her tire. Luckily she was about a half mile from a tire place and able to drive it in without too much damage. I'm willing to buy a different sized donut just to get the car home if it happens at a late hour. I'm sure having something that is a little off isn't going to do any damage. All car manufacturer's give you that dinky spare and most cars have traction control and stability features.