Which oe wheels do you have? Knowing that will solve your mystery. Once you know your wheel style number…you can go to one of the online part database sites to see which hub cap it uses. You can then shop for that hub cap using its BMW part number….and the floating hubcap equivalent.
If you click on the 11 digit BMW part number (like one the
www.realoem.com website) it will list all the other BMW models that use the same part. This again can help determine which floating hub cap you need.
EDIT: I looked up the X3 28i wheels and it looks like all of them use the same hub cap….so using that 11 digit part number…i simple googled the following phrase to find vendors that sell the correct floating hub caps for the F25 X3. Copy and paste the following phrase into a google search box: { BMW
36122455269 floating hub cap }
At least one of the vendors in the list should also give the size of the floating hub cap…and since you’re using the correct BMW part number to search with…it will be the correct size for your X3. Good luck.