You need to trace a half-circle with an utility knife. More detail is found here -
Spare Tire Installed!
Then you lay the flap you created flat with the tire. You'll need to bolt a ratcheting strap to keep the tire flay and secure (see thread above). Then you'll need some sort of support under the near edge of the tire. I'm still thinking that part over. Even with my strap ratcheted tight the tire still wants to drop a little into the subtrunk and lift up the floorboards. Prob a 2" by 4" cut to fit would work. It might need some something to secure it to the subtrunk. Could be a screw or even a piece of velcro.
Here's my pic without the tire. I had to cut a little wider than this to reach the bolts for the strap. Good luck!
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