Cupping is a irregular saw-tooth wear around the entire tire to one or both shoulders. It is a phenomenon on many cars with a modern suspension. A tire with this kind of wear makes a noise similar to a faulty wheel bearing.
To get more insight into the phenomenon of cupping and how you can do something about it I collected some information.
The cause of the cupping is vehicle related. Cupping is caused by several factors:
To give a vehicle in general, and in particular at high speed, a larger directional stability, car manufacturers provide the vehicle a non-driven rear axle with a longer toe-in. This will result in the left rear wheel to go to the right and the right rear wheel to the left. Both wheels however run in a straight line. The result is that the load on the shoulder of the tire is irregular and consequently will wear out. (Tyre manufacturers recommend in general to adjust the tracking and camber within the recommended maximum tolerance towards "zero" tune).
A (too) low tire pressure will cause "sag" and the shoulderpressure will increase. This, in combination with, toe-in, will speed up the wearing process and causes a sawtooth pattern. Increase your tire pressure and the shoulders will be relieved. (Some tire manufacturers recommend to increase the pressure by 10-15% and thus reduce the chance of cupping). Regularly change of wheels between front and rear (from 10,000 to 15,000 km) also reduces cupping.
If you're a sporty driver than your tires wear out faster while a quiet rider will get a higher milages. In the latter case, the tire has a greater opportunity for cupping.
Larger tires cup easier than narrow tires, it is also wise to choose a profile with closed shoulders. When the spacing between the blocks on is smaller larger and / or interconnect, there movement on the road surface is less (less tilt / stuffing).
A statement of Goodyear Dunlop Tires Netherlands BV is, if a tire is not used in a extreme way, has the correct pressure and rolls exactly straight, cupping will not occur..