....Would you really want to potentially risk your safety by stretching a tyre just because you think it looks cool?

Even if you have an accident which is beyond any question someone else's fault and your car is checked and found to have inappropriate sized tyres, you are potentially suddenly in very deep sh!t, especially if there is an injury in the incident.
Your tyres are your only point of contact with the road and each tyre's contact area is only the size of a CD case.
Joe - I sometimes wonder about your mindset.