The load on each of the tyres on your car is different depending on the tyre’s position. What this means is that, depending on the mounting position of the tyre, the wear-rate of that tyre will be different to the tyres fitted on other positions of your vehicle.
The Benefits of Wheel Rotation
A common example of this is the different wear seen between the Front Tyres and the Rear Tyres on a Rear-Wheel Drive car. Typically, on these cars, the rear tyres wear more quickly than the front. This is due (even with correct wheel-alignment) to the rear tyres having to cope with the driving as well as the acceleration forces of the car. The Front Tyres only get subjected to severe forces when the vehicle turns corners. This “part-time” work of the Front Tyres means that they only get subjected to tyre-wearing forces sporadically so they last longer than the rear tyres (that are constantly transmitting drive to the road).
“Why haven’t they designed something to compensate for this flatspotting?”
Well they have and it’s called “Wheel Rotation”.
By changing the position of the tyres and wheels on you vehicle, you can share the heavily loaded service positions amongst the tyre so that they all wear-out at a similar time.