Outside spare tire drag on SUV?
 

http://i46.photobucket.com/albums/f1.../blocktail.jpg

With all the turmoil that going on in back of this brick, does it really matter that a spare tire is hanging out there?

How much could it help the cd if the spare was carried inside the car?
(I'm sure it would help if I left it at home)!

leaving it off will save weight so that might help, but if you're going to carry it that would be the best spot i think (unless you could put it on the front where it might serve as a grillblock and make the nose a little more pointy...) you could even argue that in a very crude way it extends the car and creates some sort of boattail.

in the real world i don't think it will result in any measurable gains. kammback lip spoilers at the roofline and the sides might give you better FE results and at the same time might cause less practical problems.

Just don't put it on the roof!

I really don't think there will be any change in mpg on "tire in the back vs. tire inside"

Never noticed a difference on mine

It probably has no measurable aerodynamic effect back there. Unless of course you were to use it as a mounting point for a partial boat tail...

You know that if you ever back into something, that spare will cause more damage to the vehicle than without it.

That's a good reason for not having on the back. I've seen a few folks that backed into lamp posts at malls and really racked up some damage.

The Japanese CRV carries their spare inside..

Carrying the spare on the outside of the CRV makes it look more "manly". A marketing ploy. (It must be a capable machine, see, the spare is outside!) Take that tongue in cheek since I drive a Jeep... With the spare INSIDE...

If you don't want to carry it inside the cabin, you could always carry it inside the engine bay like old subarus did. :D

Leave the spare tire at home and get a AAA card and a can of fix a flat. How often do you get flat tires these days?