Does anybody know the right tyre pressures for an STI 8 running on 19`s with 245/35/19

 

As it's not an OE fit, the only way to be sure is to contact the tyre manufacturer, give them the details from the car (max axle weights, max speed, wheel size, camber settings etc) and they should be able to give you a minimum pressure that's safe for the application. You'll then need to do some testing to get the right balance of ride comfort, steering and handling to suit how you want the car to feel but you must not go lower than their minimum pressure.

Mike