I here that Nokian makes a really good winter/summer tire; that may solve your problem; Check out there website at
http://www.nokian.com
Also; there is TONS of places around that will store winters/summers for you for a small fee; many of the car dealers here in my town have rented farm land, and will lock up tires in an old trailer for something silly like $8/month
There are options if you have no space; check with the local tire guys and see what they offer for storage;
In my opinion, you should NOT compromise safety for a few bucks or for lack of storage. AWD is not the answer its part of the solution; and tires are very critical;
The OEM tires (the goodyear RSA All Season), that are likely what you have are horrible winter tires, and average at best for summer. It is well worth your safety and that of others to find a solution to your space problem, that allows you to use true, good grip winters.
I have the AWD and I switch winters/summers there is no comparing the two type in cold weather, and for traction (stop, go or tracking in turns).
I just had a friend total a BMW M3, while waiting for his winters with his worn out summers with a little water on the road... $85,000 toasted for $2000 in tires...
tk