I recently had a flat on my rear driver side. I had to drive on a donut for like a day. When I got my tire fixed with a plug my steering wheel began to shake. And my wheel turns to the right now. What could this be?

So, if you rotate the steering wheel your front tires will not turn. Have someone turn the steering wheel while you watch the steering shaft to see if you have a problem there, If the shaft is rotating then you may have a bad rack and pinion. The tie rod ends may have broker or disconnected. Also make sure that the anchored bolts to the rack are tight.

There's something seriously wrong in the transfer case or controls. It seems the rear driveshaft is locked up, and the front wheels are driving. The driver's side rear tire is skidding because it's trying to turn backward - rear passenger rear tire is going forward and rear differential has no option but to turn the driver tire in reverse (driveshaft locked). DON'T TRY TO DRIVE IT. Get it checked out and fixed.

Have a front end suspension check done to eliminate any worm ball joints -shockies- worn suspension rubbers-- steering problems. If ok have a wheel alignment done and have the rear end aligned first as it affects the front alignment. The violent wobble is castor wobble and indicates negative castor possible from sagging suspension springs. The camber is out at that results in the car following every dip in the road. The camber has to work in conjunction with the toe-in measurement and if the 2 are not correct then you will have problems.

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,

DRIVE REAL SLOW LIKE 5 MPH ON FLAT GROUND. NO BUMPS PARKING LOT.LET GO OF THE STEERING WHEEL IF THE STEERING WHEEL ROCKS BACK AND FORTH. YOU HAVE A CORD SEPARATION IN A FRONT WHEEL IF YOU FEEL YOUR SET ROCKING. THEN ITS A REAR WHEEL. THE ONLY TO FIX A CORD SEPARATION IS TO REPLACE THE TIRE.

I believe driving on the donut spare has nothing to do with the problem-it isn't all wheel drive option is it? You say you added brake fluid, how low was the level? If it is losing fluid, you might have a rusted brake line that is leaking. Any evidence of a leak under the van? It's possible the master brake cylinder is bad, but this seems to be a sudden start of the problem. Did the tire blow out or did you go out to find it flat in the morning? I believe this is a leaking brake line issue. It is possible that if the tire blew out while driving, or you hit something (like debris) in the road, it may have damaged a brake line. As I mentioned earlier, it could just be a rusted leaking brake line. If brake fluid leaked on the exhaust or any hot components, it would give off a 'chemical' smell ( or even have an odor if it just leaked out) Let me know what you find.

It is hard to say what size tire you need.First thing we need to know is the size of the rim or wheel you have on the car now.You can get this information from the side of the tire on the car.
The factory size : 15"-wheel
195/65R15 - 205/60R15 16"-wheel
205/55R16 - 215/50R16 17"-wheel
225/45R17 - 235/40R17 18"-wheel
225/40R18

I would guess incorrectly tightened or installed wheel bearing. Or it might just need to get greaced.

just keep kicking it mitsubishi wheels are nortorious for corrosion seizing wheels to the hub and make sure you clean the corrosion off before you put the wheel back on or you could have problems.