michellin diamaris #87 wheels on my 4.4i
 

sup fellas. i recently bought some 87 wheels w/ michellin diamaris already mounted on. i went to a tire shop and they put it on for me. i have a 2003 4.4i. they put the tire pressure as 45 all around i think. is that about right? oh and one of the guys from bmw told me that if i buy the 87 wheels, there has to be a conjuction with a retrofit kit wheel arch or soemthing like that. im already riding with the new rims and seems fine. any input guys?

Welcome!

45psi is way high. That will ride like a brick. Do some searching with the search tool above, and you will find many posts on 20" wheels and tire pressure. Some here go by the OEM PSI (32f/39r I think) and some drop it down to 32 - 34 psi.

Oh ps., the wheel arches are totally optional as you figured. You do not have to have them, but they do look good with 87's or any 20" that has an offset that pushes the wheel outward. There are plenty of pictures on here of X5's with and without arches/flares. I have them on mine since they came with the 4.6is (on the rear). Check my custom X page for a pic of arches and 87's. Some people added them to the front too.

thanks a lot ncx! so.. 32-34 in the front and 39ish in the back?

No problem.
It is trial and error for how you like it and if you will be carrying a load. If you will not be towing or carrying big items I would try something like 32f/35r and after a week or two adjust if needed to suit your firmness preference, your driving style, and the current weather conditions. Check and maintain your psi often, these tires are EXPENSIVE.

thanks ncx!