Bought a nice used car that came with two brand new front tires. Rear ones were garbage, so I bought two more and threw them on the back. The vehicle steers perfectly straight even under hard braking and tracks perfectly at highway speeds or at slower speeds. Is an alignment absolutely necessary at this point or can I just get by with a balance and rotate at the proper intervals? The tires that were put on were 50 something dollar Chinese tires, Ironman brand, as a placeholder until I get better tires next year.