Wheel arches
 

Does anyone know of a place for wheel arches? Also, is this a difficult DIY?

I've seen some on ebay

Wheel Arches
 

I just looked on ebay, they have some, boy are they proud of them... Not unlike anything else from BMW, but...

i got the ones on ebay for $200.
BMW x5 E70 07 13 Arch Extension Fender Flare Aero Diffuser for 20 21 inch Wheel | eBay

fitment was perfect on the fronts.
the rears had some fitment issues but they send me new rears next day air once i showed them pictures.
i have yet to fit them as it got way too cold.
for $100 more you can get the OEM ones though.
i see you said you needed them because you are going to fit the larger wheels and want to abide by the laws and not have your wheels sticking out further than the flares.

you dont need the flares the offsets arent that aggressive on the larger OEM wheels anyway.
i put on 30MM spacers on the 19" before i put the flares on and still had half an inch before i would have been flush.

sometimes it takes a little to get a response, this forum is less active then other ones

DIY is super easy by the way....dont know why everyone talks about a rivet gun,
use a flathead but a interior prytool makes it alot easier.

There's at least one excellent DIY post on this very forum.

The gun is needed for new rivets.

no its not i simply pushed them with my thumb, or use my pry tool flat side if they werent going in easy.

I don't think you understand how these rivets work.

http://gms-parts.com/images/51717002953.jpg

Yes agreed these don't just push in, well they do but they need to have the core pulled to tighten them up.

i installed them about 3 weeks ago....i am talking from experience.
you simply just push the top in..... and the bottom part that comes out of the thick side expands

no they dont you push the base in flush and you then push the skinny part it, they dont back out

You guys are talking about two different things. There are two types used to affix the arches:

https://dl.dropboxusercontent.com/u/...BMW-Rivets.jpg

The one on the top you push in and then use a rivet gun to pull the center pin to expand the bottom and at that point the pin breaks off flush with the surface. This type cannot be removed without destroying it.

The one on the bottom, you push it in and then push the center pin in to expand it. A pry tool can then be used to pull the center pin back out and remove it.

You need a plastic rivet gun for these. Something like the Marsen klik lok