[SMKS]

I would also guess gravel damage.

I don't think the tires are covered under the B2B warranty, but I think they have some kind of warranty.

However, that's generally not going to be something covered under a tire warranty. In general, the things that would be covered under warranty would be broken belts or the like. That is something that generally will be caused by the use of the tire, not a problem with the tire.

Source of this info: I worked in a tire shop for four years.

 

[SMKS]

That would be road hazard warranty and I don't think the OEM tires on the Cruze came with this - just a tread-wear warranty.

No, I'm not talking about road hazard coverage, I'm talking about an out-of-round condition or other problem covered under the tire warranty due to a tire defect.

If anyone can tell me the brand of the OP's tire, I can link to the warranty info from that company. OE tire warranties are complicated because the tire is also warrantied by the tire company. See below for more info.

It's a moot point in this discussion, though, because that's not what we are taking about with the OP's tire.

Anyway, here's the language on GM's warranty page for 2016 models:

Tires
The tires supplied with your vehicle are covered by General Motors against defects in material or workmanship under the Bumper-to-Bumper Limited Warranty coverage. Wear-out is not considered a defect, and it may occur before the vehicle warranty expires. In this case, the owner is responsible for purchasing replacement tires, or seeking coverage solely from the tire manufacturer. For vehicles within the Bumper-to-Bumper Limited Warranty coverage, defective tires will be replaced on a prorated adjustment basis according to the mileage-based schedule in your Warranty and Owner Assistance Information booklet. After your New-Vehicle Limited Warranty expires, you may still have prorated warranty coverage on your original equipment tires by the tire manufacturer.

 

[SMKS]

They are Michelin Pilot MXM4, 225/45-18

If those are the original equipment tires, then here's the Michelin book on OE tire warranties:
http://media.michelinman.com/conten...lin_PassengerLightTruck_Warranty_REV_3-11.pdf