We tend to your boots so you hit the ground running
CV boots protecting the axle joint on your BMW serve a few different purposes. First of all, they are there to keep the axle grease on the joint, as well as preventing road debris and water from damaging your axle. Because they are composed of a rubber material, they eventually crack or split causing the axle lubricant to spray out, and become depleted. On the BMW’s it is necessary to remove the suspension to replace the boot.
The outer CV boots on the front of the vehicle (on the 4 wheel drive BMW’s, such as an X5) are under more flexing and stressing every time you turn your steering wheel. Typically, those are the boots we see fail. The rear boots, (usually), do not fail until the vehicle is older or higher mileage.
There’s no mystery here, just get your car up on a lift at a shop that specializes in BMW and have them checked out. They are usually easy to see.