The system was designed so that tyres could exceed any theoretical 'normal use' stresses that could be placed upon them, this was then back calculated to give a static load rating as it was (correctly) perceived that this is the only sensible parameter that most normal persons could relate to and understand. I was shown the calculations to show weight transfer and braking forces along with cornenring and object impact, it extends to pages and bloody pages.
I run 4x4 tyres which are actually 'heavier' weighted than my Vivaro van ones! Probably because of the weight of some of these Range Rovers et al.