My winter setup is a set of 225/45R18 Dunlop SP Winter Sport M3 XLs on OEM 18x8 wheels. Since this is not an OEM setup, there is no inflation pressure guidance in the manual or on the door pillar. A call to Tire Rack, where I bought the tires, did not inspire confidence. The rep reasoned that since the air volume is the same as the 245/40R18s, the inflation pressure should be the same, but I don't understand how the 225s and 245s (with roughly the same revs-per-mile) have the same volume.
Can anyone provide input on what the proper inflation pressure is for this setup?