When you are done with that, your tread should look something like the picture. Notice how chamfering the edges gives the tread nice higlights that wouldn't be there without the chamfer.
The next thing to do is to add a bend modifier to the tread so that it forms a circle. You will have to fudge with the settings to get it to work right for you. These are my settings but they might not work for you so mess with them till you get it right.
Now we have to make the remaining part of the tire. Create a cylinder with 6 or 7 cap segments and position it inside the tire tread. Convert it to a polygon and select the polys shown in red and delete them.
Now you just have to select edge loops and move them outwards to bulge out the tire. When you are done, you should have something like the picture. That was easy.