Returning from the school run , as I'm coming onto the drive I realise the bin men have left some rubbish on the road and promptly run over a glass jar (Uncle Bens', next door's I assume). Find a fragment of glass in the tread but can't see anything else,and the jar is looking flat on the road (and I'm going to have to scrape it up as it is in my way ) . Will the tyre flatten or are they ok withstanding this sort of thing ?