Narrower tires do cut thru the snow better than wider tires do. But to use a narrower tire you need a narrower wheel. The smaller tire wont fit on the stock 8" wheel.

 

I'm currently on the Tire rack site and I don't see the LM-25 in a 235/45/17...

 

I think they are sold out like the Dunlop Snow Sport M3 in that size. When it comes to snow tires get them early as possible cause they get sold out quickly and they dont make many like regular tires. I learned my lesson, cause I could have bought the M3 snow tires with $50 rebate back in end of Oct. But stupid me wanted to wait and the rebate was over and the tires were sold out and had to buy from somewhere else costing me about $70 more and with the rebate would have be $120. Arrggghhhh

 

You can try and get a smaller size for the LM-25 225-45-17. The STi uses that size and has the same size rim.