I had the ST230's as my 2nd choice when I put our first set of shoes on our new/used coach.
When I loss two tires last year to California pot holes, I put two ST230's on our steers. About 7K on them now, and they ride well, and have no complaints.
I'll be moving these to the Tag position next week, as I replace our other 6 tires due to age. TCI Tire Center had 6 ST230's dated early 2015, very close to the same date as the two steers I have now, so I elected to go to different tire in a different size for the other 6. All dated 0416.
The one thing none of us can tell you, and the make of the tire does not matter - is how well the tires were cared for as far as proper inflation, and not abusive driving, prior to your purchase. All you can do is careful inspection, and take good care of them from here on out.
I do not know the Firestones, but others have reported to be happy with that specific model from what I recall.
Best of luck to you, have fun,
07 Country Coach Magna Rembrandt 45' ISX600
Roo II was our 04 Country Coach Allure 40'
OnDRoad for The JRNY! Enjoy life...