so your saying that the thin side wall of a tyre can hold a 930 odd kilogram car better than a 1100 kilogram car. The differance in weigh is not big enough. plus you are not talking about horozontal load more about vetical stress during cornering. the tyres are designed to take a spicific PSI to work efficantly. it's peoples safty in question, as well as increased un-predicitability when going from left to right ( and visa versa ) bends the pendulime action is increased, therefore making the car more unpredictable ( granted not that big but there none the less )