As has been suggested tyres can pick up punctures even when not punctured pre the trip, most puncturing happen where the tyre is in use.Definitely no tyres were under inflated as they were checked just prior to setting off. As we never had a TPMS at the time, I used to check them religiously before setting off. We had only travelled about 4 - 5 miles on the motorway. Cheap Ovation tyres were probably the cause.
4 to 5 miles travelling, even sub a mile and most particularly at the speeds normally used on motorways could certainly way overheat a tyre carcass.
Fact 3, there is no harm or reason not to use a higher rated tyre, but it offers no functional benefit and might cost more so this points is a matter of personal preference and how deep your pockets may be.
Not even the alteration in compliance the differing trye structure needs to gain a higher load rating?