Off the top of my head, I would proceed in this fashion:
Decide on the diameter of your tire and height of the tread block. If the block projects out, reduce the diameter of the tire accordingly
Sketch a tread block that can be radially patterned around the tire
The blocks will have flat faces at the outer circumference so create a projected surface (ring) that defines the final diameter
Use replace face to make the outer faces of the block(s) curved
Pattern the block around the tire
If you want to have some crown to the outer surface of the tire, you could use a revolved surface instead of a projected surface and use an arc as the profile.
I'm sure there is a more elegant way to do this, but this would be a starting point.
What was mentioned by Kyle is a good solution, there are many ways...
Here is a video from my collection, I hope this will help: