Sports Package 20" 335 Rear Tire (RFT) Expected Life

[Roadster44]

Hey guys,

Having my Winters swapped for Summers and tires shop ordered run-flat Bridgestone to match the fronts, which are also run-flats. Strange thing is that the fronts are in a good shape, but rears are worn. Since it's cheaper to replace two RFTs than all 4 to be non-run-flats, I approved. Still it's odd because I ran winters from 2021-2022 (Nov thru May) and 2022-2023 from December through April 5. So that should have reduced tire wear of the RFTs rears. Tire codes on rears were 0719. 7th week of 2019.

So my questions are:

What is the expected life (mostly highway driving) for Sports Package 20"
335 rear tire both RFT and Non-Run-Flats?

What can I do to reduce rear tire wear?