Something I learned about my identical caps, mine seemed to "flex" and make a speed-dependent clicking or creaking noise after I removed and reinstalled the front covers. At first thought it was a front wheel bearing making the noise. Checked the forums and it was something several other Seneca owners reported. In my case it was even starting to wear into the wheel finish where the cap met the wheel.
I solved mine by getting some 1/4" clear vinyl tubing at Home Depot, slicing it with a razor knife lengthwise so I could slip the tubing onto the edge of the wheel cover. Used 3 pieces per cover thereby leaving several small gaps for any water to escape from underneath and reinstalled covers. Now the vinyl tubing is in contact with the wheel surface, not a sharp sheet metal edge. No more noise.
Don't know if the rears have similar issues, too far back to hear I suppose.
2014 Seneca 37TS
Toads: 2014 Ford Explorer Sport or 2013 Ford Focus ST