Factory 20s with Goodyear Wranglers on mine with stock Lariat fender flares.
Mine rub occasionally when backing out of the drive.
I contacted Weather Tech and was instructed to remove them and return them for a refund. She told me to call back for a return authorization and send them back. Can't argue with that.

 

I'm living with them the way they are. The rub is only occasional in reverse with a grade change.

 

That's my plan as well.
When I get some time, I will try and see where they are rubbing.
If it is just a corner, I may just trim off that offending edge.

 

I have aftermarket wheels/tires, so I'm not exactly a direct comparison. Still, I was surprised with the amount of rubbing on my Weathertechs and needed to trim both sides more than once. Still, I feel the occasional rub when I am turning and going over a bump. I can live with it, but it is a bit annoying. I have already trimmed at least 4-5" of width from the inner part of the mud flaps, so they're about 1/2 of the width of when I bought them. It doesn't bother me aesthetically, as the outer edge is still intact and this is what is seen the most.

I wondered if the Ford mud flaps would have sit more flush and not needed the trimming, but I wanted the width of the Weathertechs for better protection against paint dings.

My wheels are 20x9", +20 offiset, tires are 305 55 20 BFG KO2's, 2" front level.

 

I have a 2016 XLT Sport with the 20" six-spoke wheels and BFG AT KO2s (275/60/20) that are about an inch bigger than the stock Hankooks, and mine did rub on the inside corner of the front flaps. I took a cut-off wheel to the inside edge and trimmed them up a bit. Problem solved.

 

Mine rub too. Only the passenger side when turned fully right. First problem I've had with a Weathertech product. I'll just trim it a bit I think.

 

Mine rub, but I've got 34" tires. I trimmed about an inch off of the inside of each with a Dremel wheel and it reduced it. I think if I trim them down to the point where they don't rub, I'll start losing basic functionality. The rub is infrequent and not bad, so I'm going to live with what I have now.

 

Factory 20" wheels, Hankook Dynapro ATM 275/60/20 rubbed on inside drivers side only. Trimmed inside of mudflap to clear.

 

How much did you trim?

 

I have the Weathertechs. My left tire ('16 Screw with 20" factory 6 spoke wheels / factory sized Michelins) would rub on the inside of the mud flap when turning hard left. It grabbed it good twice nearly pulling it off, that is when I broke out the Dremel and trimmed it....problem solved.

Just trim a little at a time periodically checking the clearance until you feel comfortable you have fixed the problem.