Fender Arch

I have an 2011 BMW X5 and I will like to change the original fender arch from the 35i to the 50i fenders.

How easy are they to replace? Do I need a special tool, like a rivet?

Thank you.

The rears you need to attach using plastic rivets available at the dealer for cheap, you also need a plastic rivet gun - you can get them from napa or online, usually in the $30 range to do it.