'05 X5 3.0i - replacing factory v-spoke wheels with 20" wheels

[wild-one]

I have been reading posts for days trying to find out, what I think is a basic question. If the answer is indeed somewhere in here, I apologize in advance for this post.

I have an '05 X5 3.0i with the factory OEM 17" V-spoke wheels. I have found some wheels (replicas, I think - I have read the very informative posting on the buying guide for replicas) that I want to buy. Here is my question(s):

The 20" rims I want are 9.5" wide (I am not going to stagger, for tire rotation purposes). From research I have done so far, I was planning on putting 275/45/20 tires on. Will I have any clearance problems on the front or rear wells? I can't seem to find any specific answers to this question.

I am buying my tires from Discount Tire, and when I went in to research a tire, the manager said that a 20" wheel on the 3.0i X5 will affect the spedometer by 2 mph, @ 70 mph actual speed. Any truth here?

Also, do I need any camber adjustment on the rear?

Any comments is GREATLY apprciated!

Here is the wheel:
http://cgi.ebay.com/ebaymotors/ws/eB...ayphotohosting