New 2017 Prius had sidewall blowout the day we bought it!

ugh, sorry to hear it. the good news is that you had a spare, and it was pumped up. not all new prius come with a spare.
all tires are 'aftermarket' so to speak, since toyota doesn't make tires. not sure what you are asking?

 

Check the tire pressures of the other tires. Maybe they're all up at max sidewall pressures, not the pressure spec'd in the driver's door decal? Or, they might have been, but the dealership quickly lowered them while they had the car back in the shop? While you're at it: check the pressure of the temp spare, it should be set at 60 psi.

This might be a red herring, just a thought: the cars come from the factory with tires set to max sidewall pressure, to avoid flat-spotting during shipping or protracted idle time. The dealership, as part of Pre-Delivery Inspection, is supposed to lower them to spec., but there's been a few reports of them goofing off on this.

Again, this could be a red herring, could just be a defective tire, and it decided to blow on the first decent drive. And per @bisco, there are no Toyota tires. The dealership actually was under no legal obligation to replace that tire; the defect warranty is typically with the tire manufacturer. In this case I'd suspect they will be compensated by Dunlop, but not sure.

 

TOYOTA only have 3 or 4 different Original Equipment tyres they install in the factory - and depends on the market. Here in Australia, they all have the same Bridgestone ECO tyre (except for the top model which has 17" wheels), but that tyre isn't used in USA.

In my experience, the Original Equipment tyres are generally the best to keep on your car.

 

The Max pressure noted on the sidewall is totally safe to operate the vehicle. But, under-inflated tires are susceptible to blowouts because the sidewall flexes more than spec causing overheating leading to failure. But, you should have gotten a TPMS warning for under-inflated, so its hard to say what caused the blowout. Glad there was no accident or loss of control involved.

 

I wouldn't be at all concerned, almost certainly the other tyres are fine, tyres have very few problems these days. There is a possibility that in shuffling from factory to transport to shipping, wharf, transport, to dealer's holding yard to dealer that someone may have been careless and clipped the tyre on something sharp, causing it to fail. Alternately, just a freak failure of a new tyre.

A car is shipped from the factory, eventually arriving at the dealer, and, the dealer has a responsibility to prepare the car for the customer. The manufacturer gives them an extensive list of items which need checking, from removing transport stickers, checking all fluids - to inducting the new owner in how to use the features of the car et al.

Back in the mid '90s, I test-drove a Mazda which had only just arrived in the dealership - the salesman said it hadn't been prepared, it still had plastic covers on the seats, and hub-caps were on the back seat. First thing we did was go via the air-pump and drop the pressure in the tyres from mid40s to 30psi - then went for our road-test. Similarly when I first drove my PRIUS, it had just come off the truck, the salesman said that the car hadn't been checked over at all, and that the tyre pressures were likely to be quite high (rough).

 

The tires on US Prius seem to be several different brands, likely depending on supply or current price. Mine has the Bridgestone Ecopia 422+ made in Japan. I think some have Toyo tires.

I too bought a Trim Two to get a spare tire. for me, the Trim Three, the only other US model with a spare tire, was not worth the price difference.

 

US Pius? Those must be from the Bible belt. ±

 

The only thing I'd miss on a level 2 would be that the touch-to-lock/unlock is driver's door only. That seems like Toyota's method of punishing those who choose 2...

If there was a base level that had 3 door touch lock/unlock, drop-kicked the Darth Vader Dash (and reinstated buttons/knobs/sliders), and ditched ALL the shiney white crap, I'd be all over it, lol.

 

I have mine set to unlock all doors (a menu setting) since I put things on the back seat a lot. I have gotten trained to use thedrivers door to unlock before opening the hatch. There is not sensor back there either.

At least we have SKS fob & not a key or just RFID fob.

 

If the TPMS was initialized with one tyre low, the warning wouldn't come on, maybe the lazy PDI guy initialized it instead of pumping the tyre up.

 

As a couple other replies already pointed out, the factory overpressure is very unlikely to be the cause. It was still within the tire's rated pressure, and for auto tires this rating generally has a very wide safety margin from its burst pressure. Blowouts from underpressure-driven overheating are vastly more common.

Many of us even leave that factory overpressure as is (when the dealer neglected to reduce it), or even add a bit more, and have no problems for the entire life of the tire set. We get better MPG and tread wear and crisper handling, at the cost of reduced ride comfort and harsher road noise and vibration.

I'm going to vote for unseen road debris. But don't that distract from the other suggests of manufacturing defect, or tire damage inflicted along the transport chain before you took possession of the car.

 

I feel both hypotheses are possible, but neither one eliminates the the other by being a certainty.
The eventual evidence may be conclusive.

 

Enjoy your new efficient car.
I have had mine for about a year now and I know mine is still enjoyable. Sometimes during the week if my wife has a planned errand with the neighbors, they ask for the Prius. I end up driving our 2006 Corolla to work.