It looks like you lost the top plastic part that covers the bolt.

 

What is that thing in the place where the Slime Pump goes?

 

Stuck up inside the hole in the cardboard/sheetrock. I just have no idea what would cause that. Bizarre

 

Mine Looks like that too,

 

You set something heavy (more than 5 pounds) down on it

To hold the plastic cap on to hold the cardboard up

Believe it or not the weight you take off the rear of the car is about 1.5 times the weight of the spare since it is behind the rear axle it transfers weight off the front.

 

Had the poke-through happen on the fiancee's trunk cardboard piece.
I fished out the plastic piece that goes on top of the bolt (it was stuck in the cardboard hole, under the carpeting),
I then used an old license plate (a store-bought one, not a real one), flipped it upside down,
duct-taped it to the bottom of the cardboard, and re-installed the plastic topper thingy.
So far so good.

 

hmmm... now it's been a LONG time since I looked underneath my trunk floor, but if I recall, I don't have that issue because my Brembo pkg meant a spare delete Unless I completely lost my mind and can't remember if it has a spare or not. lol

 

You should have what mine has: Slime-TPS killing slime pump/air compressor. I keep a jack in there too, along with tire plugs. I'd rater plug the tire and just use the compressor and get it properly patched later than fill the tire with goop.

 

That's right... I remember now. That slime!!! I've got towing on my insurance, I think I'd rather just get it towed then used that slime crap

 

Kinda funny I stumbled upon this thread. Just today I discovered I have the 18 inch spare in my trunk after thinking I had no spare and a slime kit these past 2 years. Sweet.

 

Here what I made for mine. I can throw pretty much anything I want on top of that.