Well, it's been a while however I though I'd follow up with my experience running the Pirelli Zero SUV RFT's 20" seeing there isn't much info on the Pirelli around.

Pirelli total life till reaching the min wear tab = 23,500Km.
Previously fitted factory Dunlop RFT's lasted = 18.300Km.
On my previous E70 With Bridgestone Dueler 20" RFT's = 26,000Km's.

Ok, the Pirelli Zero SUV RFT's have been by far the best tyre of the lot, they've offered us the quietest, smoothest, best handling ride right up till death, they didn't start to deteriorate in performance like the Dunlop's did at 12K and there was no bone jarring ride or droning like the Bridgestone's..

I've spoken to several reputable tyre stores here in Sydney and they all assure me that 23Km's is about average for the 20" on the E70 X5 so there you go.

I looked into some non RFT options however after driving a friends E70 with continental non RFT's I've decided to stay with the Pirelli's, I found the Non RFT"s a little soft for my liking.

Hope this helps anyone looking at 20" RTF's