replace 1 or both or all 4?

Wow, glad you're ok! Maybe just a bad tire? Or perhaps you hit something on the road? Definitely should check your other rubber for defects....

 

You are very lucky! I would definitely take it to a Bridgestone dealer for analysis; have them check your other three tires too, like Dino33ca suggested! Please let us know what they say.

 

That will depend a lot on the condition of the remaining tires. This one looks like it may have been worn thin on the edge. Any others similarly worn should go. In my climate zone, I would feel no guilt getting rid of anything with tread worn down to less than 4/32".

If you replace just one, the new one should be moved to the back, rotating the others to put two matching older ones in front. I have replaced a single destroyed tire, but the others had a third the miles of your set, and far better tread than shown in your pictures.

 

All four tires need to be replaced AND you need an alignment. Since the inside had abnormal ware.
It appears you didn't pay attention to the tires condition. That ware didn't happen in a day or two, it took MONTHS to get that way.

Your using the spare now I assume. 50 MPH is your max speed and the spare is only rated to go a few hundred miles in its lifetime. So replace them now not in a week or two.

 

If your question is whether you can install one such tire, the answer is No. If you want to use a standard tire size you must change all four tires and obviously you will also need to buy 15" wheels that fit the Prius and the tires.

 

Definitely replace both front. You might want to check your tire pressure as well.

 

what is stepney?

 

If you have Costco membership, you should get the tires there.

 

never heard that before.

 

And the wheels cost what? You almost always pay more buying than you get selling so some of the difference in tire cost will be absorbed in the exchange.

If just replacing, at least 2 and maybe 4 depending on the condition of the best two of the others. You want matching traction on the same axle.

Also factor in the cost of an alignment. And suspension inspection. That wear isn't normal. If you haven't been rotating the tires or maintaining tire pressures, maybe the other 2 might be OK but it makes a heck of a difference the tread depth and evenness of the contact patch. And we know Tampa gets lots of weather.

 

I did not see enough of the tire to determine if the wear was that uneven. The first picture suggests that it was even wear. It looks like you had a catastrophic failure along the belt line. That is unusual in my experience. Typically the manufacturer will only cover the tire as long as it has 3/32 or more of tread left and the wear is not due to alignment or some other preventable issue like under inflation. You can at least try a dealer of that tire make. Costco is decent because you can drop your car off and they will rotate and balance for free for the life of the tire. You can always have the alignment done elsewhere. Costco also includes free flat repair and covers the tire if it blows out and is still under warranty. Give them a shot. I used to buy my performance tires from tire rack and then have Costco install but they stopped installing any tires other than the ones they sell.

 

I hope your back tires aren't in the same shape or close to it.

That tire looked horrible and it looked like it wasn't in good shape for some time BEFORE that potentially catastrophic failure.

I know tires are an expense, but before that, they are a real safety issue.

Tires (and brakes) are two area's where I always recommend doing the MOST you can, not the least.

 

The rears have negative camber, do they not? In other words: they splay out at the bottom a bit. This will cause the tire to wear out at the inner edge sooner, with correct alignment. And rear camber is not readily adjustable, requires aftermarket shims.

Separation like that maybe you can get a replacement set at a discount. In any event, I'd get a set of four, if the tread depth on the remainder is similar, they're near knackered.