Alignment and Tread Depth Warranty at Costco

I'm getting conflicting info about just what my tire warranty covers. I had a tire blow out on the highway and need replacement. I had bought the Michelin Hydroedge at Costco for my 2004 Prius, and the four HydroEdges had about 50k miles out of the 90k warranty.

The middle tire depth indicators shows 4mm or more depth remaining on all the tires. However the side indicators (about an inch from the edge of the tires) have only 1mm or in some cases 0mm depth left.

Michelin's warranty doesn't specify which tread depth indicators they are referring to, and Costco is taking advantage of this to say that my tires were fully worn and therefore no longer guaranteed, because the side depth gauges were exceeded. But I would argue that because I still have a solid 4mm in the central depth gauges, that my tires still have much of their original life left.

Compounding this is that even though I get my tires aligned every 5-10k miles and rotated every 5k, I'm still getting very slight uneven wear where some sides are wearing more than other sides, and all sides are wearing more than the centers. I inflate my tires to 42/40 instead of the factory recommended 35, so if anything I should be getting the opposite problem of centers wearing out first, but as we all know there's something weird about this car that makes inflating to higher pressures necessary. Costco was claiming that invalid alignment was another reason why they could not honor the tire warranty.

When I tell this to my aligners (Wheelworks then the Toyota Dealership), they tell me that the alignment is fine and that even though some of the nonadjustables measurements have started to exceed their specs, it's all very normal and nothing to spend money fixing.

I understand that Costco and Michelin are motivated to deny valid warranty claims, but what annoys me is there's nowhere that I can find info on just how the warranty should be applied. In particular:

• Is the tire depth warranty based on the indicator that shows the most wear on a tire or the indicator that shows the least? The law that you can't drive without a certain depth is based on the least, but it sounds like the tire warranties are based on the indicator that shows the most wear.
• What exactly constitutes a tire depth indicator? There are various ridges near the sides of my tire that might or might not be indicators. And once indicators have worn off, how can a consumer know there was an indicator there that worn off without just trusting the tire shop that there was one there before?
• If the side depth indicators are warranty-actionable, and the warranty is based on the indicator showing the most wear, and there's still depth on all side indicators to support a warranty claim, can they still deny the warranty on the basis that one side is more worn than the other indicating alignment problems?
• Oh and one more thing, do I need to remain a member of Costco to get service on tires I bought there? I've gotten conflicting answers to this question.

In the end the advantage of buying at Costco is that costco at least pretends to care about not being unfair, so they will tend to respond to consumer pressure. I am going to be writing letters to them to try and get their tire shop to live up to the standards of their other business.

 

The more I think about this, the more the situation is ridiculous: For the purposes of the road hazard warranty costco is claiming that my tires are essentially fully worn because of the sides being gone. But for the purposes of the mileage warranty they will surely claim that the tires are not worn down because of the 4mm in the middle. Well they can't have it both ways; I think I need to figure out how to get them to either cover the tire I replaced under road hazard, or to get them to replace the remaining tires for free under the mileage warranty.

 

No, on each tire I have two central grooves at 4mm above the 2mm wear indicator on each tire for a total depth of 6mm. Assuming original usable depth was 10mm this means I'm entitled to 40% (4mm/10mm) back.

I also have some things that may or may not be 2mm wear indicators on the shoulders (sides) of the tires which are at 0mm (minimum, actually most are at 1mm), for a total depth of about 2mm.

 

That's another tale of woe. I try and tell Costco to inflate my tires to 42/40 but Costco always says their computers say that Toyota says 35 so that's all they feel safe doing. I've tried lots of different approaches to getting Costco to put more air in the tires, including showing them the edge tire wear, making up my own stickers for the car door, and filing complaints, but nothing will convince them. I finally just gave up and bought my own inflator so I can get the pressure back up after a Costco Rotation.