I have a spare tire and found a good location to store it. I use the post that locks down the left rear seat and tie a rope through it to two upper holes of the tire rim. This keeps the tire horizontal and when tight it allows the trunk to close. I also tie the tire using the loop post at the rear to two holes in the rim for additional support. Improvements could be made to secure the wheel better.
Is this a Donut or Full-Size Spare. Your profile is empty - what model do you have? Also, which country are you from (that would give clues about models or tyre)?