Wheel nuts

I have a 52 plate 1.6 Focus. I have had it a year and so far have not needed to take any of the wheels off. Today I noticed one of the wheel nuts looked
different. On closer inspection it appears the nuts have a cover on the end, and one of the covers is missing. I checked the other wheels and one cover is missing from the other side. I'm sure it has only happened recently. Are these covers just cosmetic? And is this a normal occurrence? I should have said they are alloy wheels, I think original equipment.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The covers are cosmetic and the weld/solder that holds the cover to the nut breaks after repeated tire removals. I have ~80k miles on my 93 SE Wagon [US] and all of the caps are loose. What I do after having my tires rotated and balanced is to take a pair of pliers and pull off the very loose caps, use the plires to crimp the opening of the cap and then tap it back on with a hammer. New lug nuts w/caps cost ~$2.50
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.