We have another Thule/BMW Power Ride roof box (Thule Motion). Now we want to mount the box on the Volvo roof rack (XC90), which is also manufactured by Thule. Now BMW cooks its own quilt with the roof racks, the grooves are wider than those of the Volvo/Thule base racks. These have 20mm, at BMW 25mm. The threaded rod to the BMW box has the mass M8x55. I have been researching in the www. for ages now and will not really be smart what to buy… Can someone tell me what suits me to some extent reliably? Thank you and greetings