This may be the same for most recent Volvos, or the C70 may be unique, but anyway, I have a 99 C70 convertible, and when I bought it the spare tire (original undersized spare) and jack had been used, and thrown back in the hole in the trunk floor and not reinstalled correctly. I cannot for the life of me figure out how to do it correctly. I have the spare, the jack, a strap and a hard dark gray styrofoam ring. I am assuming - correct me if I am wrong - that when properly insalled that assembly provides some support for the carpeted truck floor so it doesn't sag. Mine does not. Does the tire go in upside down or right side up? Where the does the gray ring go? Under the tire? On top? I have the tire upside down, the jack inside that, and the ring on that, but set up that way the ring is sitting there doing nothing.