What size of spacers should I use for front and rear respectively?
 

Hi all. I need your opinion here. When I am planning drive my X5 4.8is to off road, I will use 18" rims with 255/55/18 all terrian tires instead of using my 214 style 20" OEM rims. I am thinking of using spacers when 18" rims are fitted on. According to your experience, what size should I use for front and rear respectively? Thanks for help!

30mm rear and 25mm up front
H&R DRA is your best bet
I have 30mm in the rear and it sits flush with the wheel arch .i love it.

Thanks for comment!

It depends on the offset of your wheels and how far you want to set them out.

Rough measurement can be taken by dropping a weighted string from how far out you want the tread to be and then measure the distance to the edge of the tread. Regardless of the width of the spacer you use I suggest only spacers that secure to the rotor rather than float and include long lug bolts.

four, doesn't the rear tire touch the fender flare when the wheel goes in? It 30mm ok when you lower it or the camber helps with that?

The 30mm DRA spacer is fine in the rear, the rear wheels don't turn in like the front ones do.

take a look.A few pictures before /after the install. You've got plenty of space even lowered.
http://www.xoutpost.com/bmw-sav-foru...ml#post1000425

So, when you cruising and go over a bump or a road drop/sink the wheels will go quickly in. In this case will they touch the fender flares? Have you had any instance when they touched?

I love the look but I am worried about damaging the fenders or tires.
Another thought, how much do these spacers shorten the life of the wheel bearings? I know it will not be a clear answer but I just wonder since the bearing will be exposed to forces that wasn't design for.

Obviously a spacer is more stress on the wheel bearings, its just the nature of the beast. Many people run them without issues, just have to decide if its worth it for you.

And again even lowered having spacers won't give you a knock on the fenders or do damage. Aggressively spaced front wheels however may very well rub on fender wells or knock them just because they are going lock to lock etc