After all, the 18" was standard equipment on the RWD models, and that means staggered, 245 rear, 225 front.
I, being AWD, can't use staggered wheels. (Okay, okay, I can, but it's a mess, you need to match the rolling diameter [no problem], but then you have differing slip values, and it's just easier/better to match them)
So my idea is 245/45R18. It's a factory option on the RWD sedans of the same age, it's also used on the new Nissan Maximas as a mid-range option, et cetera. The difference in rolling diameter is about a 2% increase over the stock 215/55R17 wheels.
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