Run-flat tyres: strength

The third nuance: how easily will these tyres cope with the claimed 80 km run with no pressure? Whatever the makers claim, it is quite obvious that once the pressure in a tyre drops, the whole weight of the car ends up resting on the tyres’ sidewalls, so the load on them rises by orders of magnitude. In all likelihood the sidewall does deform during such a run - you simply may not see it with the naked eye. Nobody knows how many punctures the sidewalls’ reserve of strength is good for. But the odds are fairly high that the tyres will become unusable long before their tread wears out. That said, this is a question of economics rather than of safety.