I recently installed a pair of 245/45/18 Dunlop Sport Maxx in the rear. Since the load capacity of these tires is larger than the stock Michelin,Dunlop's 100Y VS Michelin's 96W, I have noticed that the rear tires seem underflated with 32PSI after installation. The recommended PSI for stock tires is between 32-35 PSI. I have read from tire tech on tirerack.com that 42.5PSI is the best to go for 100Y. I am living on the west coast of Canada. The lowest tempreture is about 8 below and the highest is about 30 above. Winter is short,usually 5 months.The most of period of a year here is pretty warm. I am a spirited driver and sometime drive my car on circuit. What is the best PSI I should go with these Dunlop tires for the best performance purpose? Thanks for your help.