Rear brake disc mudshields.

My 1996 90 does not have mudshields fitted over the rear discs. I have them on the front. I want to order and fit a set... is it just case of just bolting them on? Or do I need to take the wheels off?
I can see the holes but not sure if they threaded or its a nut and bolt job.
Cheers

Dont bother, they just trap mud and end up rotting the brackets any way

this is one of the things people remove straightaway so i dont know why you wanna put some on

Thank you for the good advice I thought they may prevent crap getting into the brakes. I now know better and will leave them as they are... cheers!