Living in NE USA I am already thinking about the coming winter and plan to purchase Bridgestone Blizzaks on dedicated wheels.
My favorite vendor is TireRack and I have found a decent package based on a 16" wheel. My Outie is an XLS on 18". Tire Rack always recommends minus sizing for snow tires and in fact does recommend a 16" package as well as a 17". Any opinions on the best size choice. I'll be on these for 5 - 6 months. I already use minus size snows on my Saab and Subie , but these are only minus 1 inch from stock not 2

 

The 16's will work just fine. The XLS uses the same calipers (as far as I know) as the LS/SE which comes with 16" alloys, so 16" steel wheels should have no problem with clearance. Tire size on my LS is 215/70R16.

 

How much of a difference is that going to make on your speedometer with 2" tire difference?

 

The overall diameter of the two tire sizes is almost the same.
225/55R18 of the XLS is 27.8"
215/70R16 of LS/SE is 28"

With a difference 0.2" of overall diameter you wont see a change in your speedo.

 

I have the 16 inch for my winter set on my Outlander and it fit pertly and like outpack said the 215/70R16 are the right size so you don't change your speedo reading.

 

Can the TPMS be setup with 16" wheels if the stock wheels are 18", or do you just have to live with the warning message while the wheels are on?

 

The TPMS will give you a warning because even if you get sensors in the new wheels it is not going to be programed to the system. You will be able to get rid of the warning by taking it to the dealer for them to pair them to the system. You will run into this issue every time you swap wheels.

 

Anyone take it into the dealer? Just wondering how much they charge for this? I am sure it is alot for a simple task.

 

When I traded my LS wheels for the XLS i just got the warning and I just took it to the dealer and told them that the TPMS service light came on. No explanation what so ever and they re-programed them for free. I even got a free balancing and rotation out of it.

 

I spoke to my local dealer for an estimate to reprogram for new wheels. Said it was approx $30 to hook up the laptop and introduce the new sensors to the computer. Also said I would need to have this done with each wheel change as the system can only register a max of 5 sensors at a time. I'm not planning on wasting my cash in this way so will not even have the sensors installed. Only consequence will be the warning light.