245-40-18 snow tires? Are you swapping tires but keeping the same wheel? Not criticizing, but just a bit surprised considering what I thought was conventional wisdom for snow tires. It was my understanding that, typically, a (relatively) narrower tire is better for snow.
Many people who use a separate set of snow tires for their WRX also use a second set of wheels (such as the stock wheels just as an example).
70 to engine rebuild faster than you can say "poofff!"