Yea, the problem is the tread width on replacements. The Pirelli PZero run-flats are 10.7". The Pirelli Asimmetrico are the same.
All of the overall widths are close - 11.5-11.7, it's the tread width/contact patch that is smaller.
Sumitomo HTR Sport - 9.8" and H speed rating (130)
Yokohama Parada Spec-X - 10.2"
Falken Ziex S/TZ05 - 9.8" and H speed rating (130)
Hankook Ventus ST - 9.8"
Toyo Proxes ST II - Unknown width
Nexen Roadian HP - Unknown width
Fullway HS288 - Unknown width
Nankang N990 - Unknown width
Nankang SP/7 - Unknown width
The General Grabber UHP is 10.6" and looks to be the only option. I don't have any experience with General tires though...
Research is a PITA
2014 Max Steel GC SRT, built by the bad boys at JNAP
Livernois built 392 and Whipple Kit