@RossoStelvio The price: when I ordered my car, I initially selected the optional $450 spare tire. The dealer told me that if I did that, the tires would not be run-flats. So, with that information, I chose not to get the $450 spare tire. Then, when the car was delivered, the tires were not run flats. (And, of course, I had no spare tire). Turns out that no Stelvios come with run-flats. So, because the dealer told me the wrong thing when I had spec'd out the car for the order, they sold me the spare tire kit for the option-list price of $450. But, if you go and buy the parts from the parts department it'll cost twice as much.
The foam: In the trunk are four anchor points that swivel. The anchors also serve to secure two carpeted hold-down strips that run longitudinally on the trunk floor; one hold-down strip on either side of the spare tire access panel . If you swivel the anchor up, a torx-head screw is exposed. Unscrew all four of those. (see pic, it's worth 1000 words)
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Fold the rear seats down. Remove spare tire access floor panel. Remove the two hold-down strips.
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Now the foam can be removed and installed. ( I know the first photo shows the spare tire installed, and the second one is the old foam... it's the only pics I have on hand to show the foam hold down strips installed and removed)...
Bracket. The bracket attaches to the sheet metal trunk belly with three bolts. There are three factory predrilled, threaded holes in the trunk belly. The factory covers the holes with pieces of foam tape. Remove tape and screw the bracket down with the three bolts listed in my parts listed in my previous post.
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Sorry about the poor quality pics, but they should give you an idea of what I mean.
Installation of the spare tire will take you 15 minutes if you take your time.
Good luck,
Ed