I have recently taken delivery of an 07 G35 Journey. I live on Vancouver Island where we have mild winters but every few years we do get snow. Now I may just leave the G at home in the garage while there is snow on the ground but I wonder - can I buy 2 snow tires for the rear only without it being a problem ? I always hear that you need to have all 4 the same but a number of years back I would just do snow tires on the rear of different vehicles I owned. What to do ?

 

Two on the rear will only help you get moving straight ahead. They won't help you much with stopping and not at all with turning.
If you can't turn or stop properly, you're better off not being able to get moving in the first place.
If you don't have enough weather to justify dedicated winters, go with good all-seasons with lots of tread life and be extra careful.

 

If you go with dedicated winter tires, I'd get 4 wheels and tires. In your case since I'm assuming you have another winter vehicle, I'd suggest getting 4 all season tires for year round usage and just in case you still want to use your car during those non-snowy days. All season tires tends to get better tread mileage compared to summer tires anyways and summer tires aren't meant for cold temps.