My thought
 

I have a very interesting or stupid question for all.

When I bought X5, I upgraded the wheel to 19" w/ sp. Of course, I paid whatever the price was for the wheel.

Here is my question. X5 comes with 18" wheel. When you upgrade, you have to pay for it.

Then, don't you think we should get both 18" and 19" wheels since you paid for 19" and 18" is standard that comes with car.

Just curious.

There is a cost to upgrade to bigger wheels, but not the full cost of a 2nd set if purchased from the dealer.