I dont know if this is hijacking the thread or not, and sorry if it is, but I always hear about people having trouble taking the tire down and wanted to share my tip.
To get the tire up on the roof, Stand directly behind the truck. Take the tire and lift it up so that it is vertical on your chest and the weight is resting on your forearms. Getting it off the ground is the hardest part. Now, you can kind of shimmy it up if you arent strong enough to just lift it and get it to touch the black wind/rain deflector thing above the rear glass. I dont know its purpose, but its very sturdy. Use that to slide the tire up and it will tip into the basket. Now, just stand on the sliders or open a door and stand inside and flip it over the rest of the way. To get it out, repeat the process in reverse.
Probably hard to follow, but it works for me. Takes very little strength and is pretty safe.