Depending on how you break, the rear can get more where then the front. The engage earlier to reduce nose dive on light braking with the fronts coming on harder under heavy braking.
So the front (done by MB) had a pad swap. My guess is the front pads at 26K were about where yours are at 52K and where done either as part of the CPO program or a dealer $$$ maker.
Good to hear the front rotors look good, but is the thin gap and corrosion behind the rotor that seizes it to the hub.
Not sure what the factory uses, but I have had Zimmerman rotors for Audis and the coating is not much more than zinc spray paint. It works well to prevent rust in shipping, and maybe acts as a layer of anti-seize.
Centric makes several different types of rotors, so I don't know which you had on the Mazda. You also said you had calipers replaced, well a hung up caliper can certainly cook even good pads.

You keep worrying about Chinese crap, but there is plenty of US and EU crap out there. Some of the worst stuff are the "Show Brands". Centric is a big OEM so they know what cars need.
You also keep referring to the weight of these trucks, they are beasts, but also look at the size brakes MB puts on. I bet in terms of weight per swept area, they are not loaded much more than light duty trucks.

The 320 is just about as heavy as the 550 and I have never been close to fading the brakes, even towing a 3500 LB camper or a 7000 LB utility trailer.
Yes, they have electric brakes, but the vehicle still ends up with extra load.

I noticed in one of your posts, you mention having an aftermarket tune? How does that fit with your "MB Engineers know best" logic?

Jeez!! Every time I think the subject is over, you come up with more stuff or have a misunderstanding of what you read.

I said the REAR brakes had the pads replaced at 26k miles. I also said the front pads and rotors had been previously replaced by the previous owner. But I just looked a little closer at the service records and it says the front rotor(s) were replaced at 7000 miles, but didn't mention pads. At the same time, they replaced front strut(s), tires, a wheel and did a 4 wheel alignment. I can only assume that the original owner hit a nasty NY pothole and did some damage to the wheel, strut, and rotor. There wasn't any accident that CarFax picked up. It didn't mention pads being replaced nor was there any more mention of front pads and rotors ever being replaced in any other service records. The original owner had extensive service records from that dealer with no other dealers or service shops showing up in the records. So if that's true, the truck got over 50k miles out of the original pads and a second set of front rotors that lasted over 43k miles. Pretty amazing.

I don't think that Centric is OEM on any car. They are strictly an after-market company that sell their branded products that are manufactured in China. If you have proof to the contrary, please present it.

Regarding the tune, MB leaves a lot on the table with their turbo-charged engines, especially their 4.6 & 5.5 V8's and 5.5 & 6.0 V12's. It's easy to safely get over 100+ hp and 100+ lb/ft of torque at the wheels out of nothing more than a tune....plus better gas mileage as the tune is helping my truck run more efficiently when not under load. I can now easily get over 20 mpg cruising at 70 mph on the highway. MB obviously tunes their turbocharged cars very conservatively if these kinds of numbers can be achieved with a simple tune. I've heard of others pushing over 700 hp out of the 4.6 with a tune, down pipes, and CAI. Not sure I'd want to push it that far as 550 hp is plenty for me. My truck will eat C7 Vettes and new 5.0 Mustangs alive. You should see some of the looks I get from those guys when they are in my rearview mirror. Regarding the power their getting out of the new 4.0 V8's, I don't see how much more power can be squeezed out of those smallish motors since they already have over 600 hp and 600 tq from the factory. But I'm sure there are guys tuning them for more.

A) You keep adding to the story. You can't blame me for not knowing what you have yet to say. 50K from brakes is not all that amazing.

B) From their web site.

C) This is so backwards to your Tire Pressure argument, that it shines the light on your foolishness in the other discussion.

Tuning for more pawer is easy, but (as with the tire discussion) you are simply moving to a different point in the mix of attribute compromises.

Your "absolutism" in what you think you know is interesting. I'm usually hired to fix what guy like you has screwed up.

For a 5800 lb luxury SUV, 50k miles out of the original pads IS amazing.

I found this:
Nothing foolish about following the recommended tire pressure stated by the manufacturer. I'm still confused as to why you are so worked up about that.

That's funny. Pot, meet kettle.

Since I've offered you help & advice and you keep criticizing and throwing insults at me, I'm just going to unsubscribe from this thread and any other ones that come up in the future where you carry on with the same behavior. I've met people like you before and they are seldom happy in life because they cannot accept that they are ever wrong about anything....when it's clear to everyone else that they are. I hope you get over yourself and find happiness in your life.

Lol!
Dave-isms.
A) Not following the Mercedes recommendations on tire pressure is foolish and dangerous because the Mercedes engineers know best and that is the optimum all attributes.
B) Aftermarket tuning for additional power is a great idea because these engines have lots of potential that's not released in the factory tune.

Dude I'm not insulting you, you're insulting yourself!

And by the way, if you want to find out if a company is an OE manufacturer you want to go to the corporate website not the brand website.

it's almost like you were looking for the wrong information but I would never accuse you of that.