Originally Posted by ECS Tuning

Kiet,
I typically prefer to use longer bolts over shorter bolts. But without having an X5 with your wheels that i could test fit the bolts on I can not say for cretin the 43mm bolts will provide you enough full rotations to properly attach the wheels to the hub with the spacer. The longer 50mm bolts may bottom out and there for not snugly hold the wheel to the hub causing more issues.