Had to buy two new tires

[EMD360]

I just had my tires checked for wear in September and they were fine. I notice a few weeks ago that one side of the duallies was going flat. I refilled and tightened the extenders. I have not been driving the RV much since September. Hardly at all. I refilled the completely flat tires again when I returned from another week long airplane trip just to take it to the tire shop. I noticed at least one of the duallies had a nail embedded in the tire.
The tire shop asked if those tires were put on before the others because both duallies were essentially bald but none of the other tires were. It could have been a sales technique but I realized those tires were now unreliable. So I had just those two tires replaced with less expensive Rocky Mountain highway load range E tires. One old duallie and one new tire on each side. I didn’t replace all because they didn’t have anything I wanted in stock. I will have to replace them all in the next couple of years for aging out. They are 2017 tires.
So do tires that sit flat for a week or two actually lose tread? I doubt it somehow. I run a TPMS on extenders. I don’t think I’ve been driving with them under inflated.
Discount tire said Rocky Mountain is a relatively new brand made in Utah. They were about $140 each. I have liked Michelin LTX M/S2 the last two times I bought tires. That is what is on this RV from the factory I believe. Even through the recall they lasted a long time for me. But I think they are now replaced by the Agilis cross country. So there are several more contenders. Who knows what will be the “best available” in 2023?
After the fact I realized I could have put the new tires in front and kept the four duallies the same. I’m getting it aligned in the next week or so. They would rotate if I asked. Does that make more sense?

[EMD360]

I have tire assistance but not tire insurance. Assistance is a pain because I don’t have a spare which means it would have to be towed. So need to be vigilant. I should have asked for the actual depth of tread but I was already pretty decided about what I would do. Except it does make more sense to put the new ones up front. Oh well. Hard to think of everything in an emergency.

[PartyOf_Five]

At 31' and rolling heavy we almost max out our load range, but so long as your front axle is ok with Es then it makes sense to me to have the newest up front.

Tread wear and going flat shouldn't be related, DT should have told you how many 32nds of tread each tire had, and also explained that 3/32 is the minimum DOT allowance. You could use that to judge how conservative/ customer-oriented they were for you vs a sales technique. Also the nail may have been covered in your road hazard warranty if you'd bought it.

What's curious is why 1 side was bald vs the other, especially if both were equally inflated and monitored with tpms. Otherwise my first guess would have been that 1 was low, and so the other took the bulk of the load and wore out quicker.