My spare tire (donut) ruptured. I need to replace it. Any ideas where I can find a replacement...or what else could be used as a spare?

The temporary spare is very narrow as will be the space available for storage. If you want an answer then I suggest you measure the storage compartment HEIGHT WIDTH AND LENGTH and come back and pose your question.
The first problem you will have is to get a wheel that will fit the car that is not too wide for the wheel storage area. If the available wheels are all too wide then you will will not be able to store a full size spare in the storage compartment. For that vehicle the available full size wheels in the correct bolt pattern will not be less than 6 or 6.5 inches wide.

can be either option for full size when buying vehicle look at tire if looks different than what is on vehicle its a donut spare if looks like the other tires its a full

Should say on tire itself. Not sure what tire is flat but always put spare on the rear.

I don`t think you have cv axles in the rear of that.My guess would be wheel bearings could be grinding. Donut spares are strickly to be used for short periods of time and not to be driven at any higher rates of speed. Some damage may have occurred during the actual incident when you had the flat initially.Damage to the rear axle itself,

Try rotating your tires from front to back. It may help with the noise. Get a front-end alignment which can also help with the noise by correcting a "rub" sound that originates from the 2 front tires fighting each other for control.

The place which replaced your bearings is probably correct. When you get bad bearings they do not always fail evenly across the 360 degree turning of the bearing race. If you imagine a donut with a flat spot representing your bearing- as the donut spins with the flat spot cause by a disintegrating roller, the tire is bolted to the donut. The tire is going to hit the pavement differently every rotation because of the play in the bearing is at that same spot.

This play will create small cups in the tire shape at the low spot transmitted by the bearing. When you replaced the bearing , the marks in your tire tread remained. These edges need to be worn off. Or some tire stores can Shave a tire, in an attempt to make it round again.

If you have a normal size spare, you can put the spare on the left front side of your vehicle and see if the noise goes away. If the rims are different on the spare, you can have everything remounted and pay for rebalancing and put the unused spare as a front tire. Then you know the spare is at least good as a spare, but noisy.

You can call your local tire shop and they can order a temporary spare or stock replacement rim and install a tire or they may have something used.
The other option is to check with your local auto salvage yard, they would have either style of tire and the cost would be considerably less.
There is a parts interchange to check for used parts at reputable auto salvagers in your area this is the link to check their inventory and pricing.
www.car-part.com

Hope this helps.

in the back storage area there is a circular plastic cover about 1.5" wide. pry this up with your tire tool and you'll find a hex nut. use the tire tool to loosen that nut and the tire will lower on a wire rope with a T handle in the center of the donut spare. reverse the procedure to replace it making sure you snug it tight.

if its what they call the little donut spare try to get it removed a.s.a.p., by law you are not supposed to run it over 40 miles(not per hour) i mean total 40 miles and if your in a hot area i suggest much less they are made only to get you to a tire shop or car dealer

It should say on the Donut Not to exceed 35 Miles Per Hour. It is OK to drive on, Just make sure that it is Properly Inflated and you do not go too Fast as it will shred the tire and you will have a Bigger Problem!

Spare tireSpare tireYou might find that some tire dealers will give you a trade in value for the new donut spare.