I just bought a new vehicle with P235/55R18 tires on it. I know it's only August, but I'm thinking about ordering some winter tires and rims before fall, so I don't have to worry about it later. I plan to definitely go a smaller size, so either P225/65R17 or P215/70R16 are OK, I think. Lots of people recommend going 1 inch smaller, but how about 2 inches? What do you recommend?