Z45

Some tires have more tread depth thus a different circumference. Tread depth will vary by type, brand, and model. https://www.tirereview.com/science-behind-tread-depth-passenger-tires/

Dirt settles in the door drain holes and traps water....lower corners of inside door skin.

These codes don't automatically clear if you fix the problem?

I have the GMC accessory (REV) cover installed by dealer. Ordered with the truck. They did a very good install job, can't find a single issue. Some water gets in around the tailgate but no where else. You can see daylight around the tailgate but that's not the covers fault. Installation is means everything. Guys at my dealer were seasoned pros, not inexperienced here today good tomorrow types, like many dealers employ for these jobs. I don't mind paying for a professional job.

Tires of different brands may have different circumferences (or radius) even if they are the same size.

Problems are blown way out of proportion due to the internet. The same experiences get repeated over and over again till it sounds like a real problem. There is NOT an vehicle out there that does not have some issues. Building 100's of 1,000's of vehicles with 1,000's of parts from various suppliers all over the whole, some quality control issues are going to make it through the process. The internet is full of misinformation often designed to change readers opinions. I have had 2 trouble free years with my 2024 Sierra, don't tow anything heavier than a 2026 Ranger NorthStar and mostly a around town. I personally know 3 others with same engine and no issues, 2 are LM2 version and 1 is the LZO, all three happen to be GMC's. All of these owners are older persons (40+) so that may have a lot to do with it. No modifications, no big tires, suspension hacks etc, just normal use. One who has a 2021 LM2 has over 100,000 miles and travels estimating projects for the electrical contracting company.

Was back in early June 7th as I recall

Don't know if all will be able to see this. Valvoline Cuts Dexos Claim from Synthetic Oils https://www.lubesngreases.com/lubereport-americas/11_27/valvoline-cuts-dexos-claim-from-synthetic-oils/

dexos began as an effort for GM to control the oil change market because the Quick Lube Industry was eating into dealer service department profits big time. So they attempted to get other oem’s to develop standards as well and that would make it hard for Quick Lubes to compete because all the oems would be different. GM faced lot of industry push-back, mostly the quick-lube industry and they went to licenses. Still GM it making a ton of money (est'd 30-40 million in 2025) off the license structure as they charge a hefty fee to get oil tested then require a royalty on ALL gallons sold applicable to GM vehicles.

I would be surprised if the diff's were not filled (with the cheapest gear lube) at the axle factory before being shipped to GM. If you ever watched them building trucks they install the axles and all suspension parts with the frame upside down and then turn it over before its time to install the engine. Too much gear lube in a axle can be worse than not enough especially with a lower quality GL where is get whipped up with entrained air (foam) weakening its ability to lubricate.

https://www.gmc.com/future-vehicles/2027-next-generation-sierra-1500?evar36=B2000016304.OP_EML_GMC_OW-2_DRE_CA_REV_T1-2_REV_20260625..V7_-1305730338&evar110=M_IMG_SIERRA_2&hid=E3F70EF51E5951E3EC37EF6993D5EDA5B6D0343007DE7D3E13A28BC2984F3FC59

Kind of hard to answer a ? like this without a part number and brand of parts?

Lake Speed is drumming up business for his company just by being in the spot-light so he has a vested interest in stoking the 0W-20 fire. IMO

1Based on independent testing of OE 0W-20 in the Peugeot TU3M Wear Test as required by the dexos1 Gen 2 specification.