I have a 2010 G37xS sedan - struggled through a rather slippery Canadian winter last year so now I'm looking for winter tires and wheels. Some tire retailers are telling me I must stick with the 225/50/R18's but other say I can downsize to 225/55/R17's. I'm hearing the Blizzak LM-60 is the best tire (also most expensive) but I'm also hearing that the tread wears quickly. Any advise?

 

Firstly.. It's 'advice'
EG. someone gives you advice when they advise you =D

Anyways, If you are looking for a dedicated winter set on 17's then you should definitely go for the Blizzak WS-70 (225/55/17) all around. On the 18's ur best choice would be the pilot x-ice Xi2.

The LM-60 has the same tread pattern as the WS-70 (mostly) but the compound which comes in contact with snow and ice is very different since the LM is a performance winter tire and not a snow/ice tire. The WS is unavailable in the 18 in size.

SUM - the WS-70 = best tire for snow/ice (17 in only)
- x-ice Xi2 = best tire for snow/ice (18 in category)

 

In general, you want to use the smallest width tire, but one that will retain a similar diameter to your stock setup. Taller sidewalls will also help cushion the car when you hit those bumps/potholes you can't see under the snow/slush. From what i've read, 17" should work if you don't have the oversized brakes.