Bicycle Mechanics - Woobly Tire

I got the nuts and thanks for the help. But the reason I was removing the tire was that rear tire rocks from side to side I think the problem is with the way the bearing are fastened on the axel. If I tighenten them too tight the axel won't spin, and too loose the tire wobles. Sometimes I get it just right but it comes loose after a few blocks of riding and eventually gets so loose the tire gets stuck against the frame. Any suggestions?

What kind of bicycle?

Good quality bikes have a lock nut that tightens against the cones so that they will hold their adjustment. Some department store bikes don't have them. If your bike didn't come with lock nuts, you can probably get an "axle set" at your local bike store. It will come with a new axle and all of the cones, washers and locknuts and axle nuts necessary to rebuild your hub.

For about double the cost of the axle set, you can get a whole new wheel.

Its a Trek 820.

There is also a good chance the bearings/hubs/cones are damaged. So you get them adjusted on a "high" spot and then the wheel turns and the adjustment is no longer valid and you get wobbly wheel.
The time has come to take everything apart, clean it, and look closely. Then replace anything that is bent or not smooth and shiny. Also for a Trek 820 you can probably get a new wheel for less than $50, if needed.

I took apart cleaned it, and changed the bearings, I got it to work and took it on a short 5 mile ride and it held up, thanks for all the help. It was broken since late fall now Ill have my bike for the season!!! Thanks again.