I have a 2004 with the sport option(235/45-17 tires). I need to buy winter tires which I will be installing on the 17" wheels. I read that going to a narrower size tire would help grip on snow and ice. Would you guys recommend a 225/45-17 which is a shorter(smaller overall diameter) tire or a 225/50-17 which is taller than the original tire?

 

If it were me I would stay with the regular size. the difference between a 235 and 225 is 10 mm across the width of the tire, the tread difference will be less than that. It's less than a 5% difference and I don't think you will notice. If you really want to change up, go with 16" wheels.