Well it seems if the 19,s are not on the placard then the rating is up to you so I would suggest you talk to a reputable tyre company and get some solid advice . As it has been reported get the combination wrong and it could be disastrous if an accident happens , if for instance you are to blame for an accident your insurance company would be well within their rights to refuse your claim and leave you with the bill for both cars . Next if an injury or worse a death was involved you leave your self open to criminal charges . I used to do lots of vehicle mods and certify them for Qld Transport and the legal side is scary . We replaced a bench seat in a Holden ute many years ago we fitted bucket seats from a Caprice of the same model as they bolted to factory points already in the ute so they were legal , any way the car was involved in an accident with the passenger being killed . The police and transport inspectors turned up at our workshop checking what we had done , it turned out that someone had replaced the disc pads and forgot to refit a pin causing the car to spin out of control hitting a bridge pylon . We were told they were pursuing criminal charges of wrongful death due to the brake problem and needed to check that what we had done did not also contribute to the death . Its a legal minefield and for a few minutes we were S***g bricks until it was sorted , the insurance company were going through every single thing done to that car looking for a simple non compliance with the ADR,s so they could shift blame . I don,t like to scare people but you do have to be careful !!