Tire woes -- big time

I am stunned about tire wear, and need some advice on a good tire for my 2017 Boxster S.

I bought it in May 2018, with only 258 miles on it. Came with Pirelli P-Zeros front and back. In late September, at 5,600 miles, my rear passenger tire was completely run down, with thread showing. The other rear tire was almost there as well. I do *not* drive aggressively. Mostly local street driving and highway driving. No track. On the highway, I rarely exceed 80-85 MPH.

I replaced the two rears with Bridgestone Potenza S001. Now, after just 3 months and 3,400 miles, the tread is down to about 2/32's. I'm like "WTF???"

This is my first Porsche, and I didn't expect to have to replace tires twice a year (or more).

Immediate question: What kind of tire will give me, shall we say, "a bit more mileage"? (FWIW, I live in Florida, so winter weather is not a factor.)

What's a reasonable expectation of tire life here? Like I say, my driving is tame.

Suggestions on tire type would be greatly appreciated. Insight into realistic expectations would help too.

Right now, I can't drive the car, because I picked up a nail/screw. Tech wouldn't repair it because of the low tread.... So I'm kinda in a hurry.

Thanks. And Happy New Year!