Bought these wheels a couple years ago and they didn't come with center caps and I didnt really want to pay the $40 to $60 for a set of these..... so no caps. Last summer I was setting outside on the porch and the two items came together and now have 4 center caps for about $10 and about 1/2 hr of work.
(Note: this most likely will not fit or work on just any wheel, not responsable for any injury or damage)
Step 1: Measure for fit
Measure wheel cap opening and fence post diamenter.
(Note: for options - big box stores do carry a couple of different sizes.)