Why are my tires wearing out like this

Negative.

Pretrip !!

That is a heat damage issue from underinflation, sluffing the centers off from flex.... Usually less than 90 psi..... You see this allot in tires that have been ran flat and damaged.

I'm very familiar with those drives and just by looking at them it's probably under 80 psi if not almost flat.

Long term, those casings are junk they're highly likely to have a blowout now.

 

Rotation time. Like an X....

 

Only saw this once. Hope you are correct, as i couldn't figure it out for sure. I thought poor rubber compounds. But those Michigan (my dads one driver called them) tires supposed to be #1.?

 

could be. this kind of wear is not related to alignment .

 

The inner edges are slanted too...this I can see often... is that a part of under inflation or alignment? Could it be also bearings?

 

It looks like you were spinning your tires on a rough or loose road surface while empty or in bobtail. I say this because when there is little weight on the drives I would think the inner drive tires will make the most contact with the road, but I could be wrong.

 

I suspect his tires may not be virgin Michelin tires. I think they are recap tires with Michelin tread.

Edit-

Never mind. It looks like they are Michelin tires. Some fleets like using recap Michelin tires on their used leased trucks.

 

Close but on spinning & gravel use, you will see matching patterns on tires across the whole axle.. it can present sightly more on inners but if you look at the other tires you'll see the problem tires are isolated mostly.

There can be a combination though, as the tread block on new tires is very high it is also susceptible to the most amount of flex and actually can run hotter. Usually seeing this type of damage means that the tread temperature has been 160 F or higher.

The inside tires are the most susceptible to heat and if it is underinflated that's even worse to produce heat.

Pressure pressure pressure needed to stay cool guys

The difference between 100psi and 120psi on 90F+ days is about 20° , plenty to put you at the danger zone of 160°F(+) especially if loaded heavy or driving 65+ mph.

If you wanna watch this buy a laser temp gun and track the tread temps on hot days, you'll see a big reduction in temperature using higher cold inflation pressures.

This correlation between temperature and pressure is hyper critical on Super Singles loaded heavy in summer heat. They must be 120 psi nothing less.
If you use 120(cold) on regular duals it drops tread temps significantly.

 

Looking at the pictures again, you can see how both the inner rear tires have the most damage. I’m starting to think it may even be the rear axle shocks. A PSI check on his tires in cold state would also help in finding the problem. I honestly don’t see how it could be under-inflation as the center wear is attributed to over-inflation. Maybe I’m missing something.

 

Low on blinker fluid?