I'm not so sure about that. While Bridgestone doesn't supply load ratings on their website, for the very similar Michelin PS2 tires:

225/45R17 = 1356# @ 51 psi
245/40R17 = 1356# @ 51 psi

At full inflation pressure that's total rated loading of 5424#, versus car ( 2900# ) plus load ( 400# ) for 3300#. True, at only 40 psi the load rating is reduced - but I don't think by 2100#. Unless Bridgestone rates their tires differently than Michelin, I don't think the weight limit is due to the tires. More likely it is due to spring compression placing the suspension too close to the bump stops. Hitting the stops on a hard turn could spell disaster in this car with its high cornering loads....