Originally Posted by planman

As the suspension compresses, the rear axle moves in an arc because we have control arms instead of leaf springs. (With leaf springs the suspension would travel vertically instead of in an arc.)

Think of your old physical science class.

The lower control arm is a fixed length & will push the axle back & up as the coil springs compress.

The only time the OP's tire would rub on the end cap is when he is aired down enough so that the tire bulges out on the top 2/3 when he bounces over something in the trail with the bottom 1/3.