just go by the max pressure on the sidewall.
The max. pressure on the sidewall isn't a good indicator of what you should inflate them to, it's the suggested max. pressure for the tyre itself.
The pressure you want depends on your car hence why manufacturers suggest tyre pressures, they take into account the weight, suspension, etc. and what tyres they did all the tests on.
Since new tyre compounds have been invented since your car was produced, you can inflate to the tyre's max. pressure then adjust it according to your driving style, it will probably feel right somewhere between the manufacturer's suggested pressure and the max. pressure of the tyre.
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