Cheap tires for sale are not exactly like fashion when it comes to finding good deals. Or maybe ski equipment would be a better example, at the end of the winter ski season is always the best time to get snowboards and the like at a big discount. The same is not exactly true for tires because they tend to not be compartmentalized into seasons. Winter tires are made specifically for navigating through the snow which makes them more vulnerable to warm weather driving; simply put you could get 3 or 4 winter seasons out of winter tires, where if you use them year round they will be worn out in 12 month. Because of this the tires are usually on sale at the end of the winter season, so between March and May is usually the best time to negotiate some tires for the next winters season.
Its harder to get other tires for sale because their useful season carries over or can be switched out depending on the weather. If you want to get the most for your money you should get a set of winter tires, and a set of either performance tires or all season tires. This way you can switch the snow tires out in the fall and get more overall life from the set over a few years.
It is possible to get better deals when there are overstocked tires or business chains that are going under. While tires are advertised at different prices what is not advertised as well is the service that accompanies the set. Some companies will offer more in the way of service while some offer next to nothing. I have found Discount Tires to be the best combination of service and price. Find out what the make and model is of the vehicle you own and then comparison shop a few different chains, and never be afraid to ask the store owner if that is the best he can do on price.