Definitely got your money's worth at 9 years and doubly blessed that the tire separation started but you caught it before it caused any problems. Our fifth wheel came standard with LR E 10 Ply and when we replaced them recently due to age and tire separation on one, that caused damage, it was replaced with the same. Never had to ask for them. We got a good warranty too. What we didn't know was the on the original, they had rubber valve stems. When the tire shop put on the new ones, they specifically put on metal valve stems.
Glad you made a good decision and are sticking with it. It's your rig and making the best decision is important.