2007 BMW X5 E70 pulley issue
 

Dear ALL,

I have ordered mechanical belt tensioner with 2 smooth pulleys (non-grooved) attached.
when installed into my car 2007, BMW X5 (E70), I see the ribbed belt side is contacted on smooth pulley (grooved to smooth).
usually, ribbed belt will slip on grooved pulley otherwise belt will damage soon. it means smooth to smooth and grooved to grooved
please advise is that BMW designed or I have something wrong? or is there any grooved pulley for replacement?
I have attached picture for your reference

thanks for your advice.