Spare tire requirements

[Ski_Pro_3]

Last year I got a set of Rickson steel 19.5" SWR style wheels and 245/70R19.5 tires. A set of 4. Now I'm looking into the spare. My current spare is a stock 2006 Dodge wheel and tire, neither of which, has the load capacity I need.
So, in my pursuit of attaining a 19.5" spare, I have a few questions;

1. Will a 19.5" tire and wheel of the above mentioned size, fit under a 2006 Dodge 2500 4x4 diesel short bed truck? Is there enough room and will the crank/pulley device support the weight?

2. I can find a Vision Heavy Hauler 81 Series Machined Clear Coat Wheel (19.5x7.5"/8x6.5") on Amazon;
http://www.amazon.com/Vision-Heavy-Hauler-Machined-19-5x7-5/dp/B009F9MF82?ie=UTF8&colid=ZO07J7YSGGZ7...
I'm pretty sure this is the size I need for my truck. Can anyone confirm that?

3. Since I have steel wheels and the Vision wheel is aluminum, will I need different lug nuts for the spare?

4. Will the lug nut torque be the same value as with the steel wheels or is it different?

5. Does the tire have to be the same size as the other 4? I don't plan on rotating it. If I ever use it, it will be only for long enough to fix my original tire or to replace the original tire. I'd like to use a smaller, lighter tire than the running size for a spare if it's safe to do so. Even a used tire if I can find a good one for a good price.

Any thoughts or ideas would be appreciated on the topic. Discussion of the necessity of a spare can be in another thread if that's alright to keep things on topic here. I'm mostly just interested in the pros and cons of using an aluminum wheel and off sized tire for a spare considering my 4 tires in use.

[gbw]

You may have to kick up the size of the spare tire but I would just reuse your 17" rim. Look for a tire roughly the same diameter as your 19.5" ones. As Kohldad mentioned, if you have a rear blowout, take the front tire off and put it on the rear. Seeing as so little weight goes on the front axle with a camper, you won't have weight issues with a standard tire with 17" rim on the front. As mentioned, I wouldn't be doing a nascar race with a somewhat mismatched front but I'd feel comfortable to do a few hundred KM's at a slightly slower speed

[boogie_4wheel]

kohldad wrote:
In this regard, the stock spare should work with a little extra effort of mounting the spare on the front and then moving the front 19.5" to the rear.

This is what I would do.

[kohldad]

How common is the 19.5" tire, i.e. how long will you have to drive on the spare?

If you are using the spare as a get me off the road to the nearest tire store or campground, then a different spare should not be a problem with a couple of caveats. On the front will pose steering issues, on the rear it could cause problems with the limited slip. In newer trucks it would also effect sway control and the other automated safety systems.

In this regard, the stock spare should work with a little extra effort of mounting the spare on the front and then moving the front 19.5" to the rear.

If you want to continue on your way at highway speeds, the tires should be the same size or it will create steering, handling, and limited slip issues.