The Maximum Data Rate on the 5GHz radio is 1300Mbps, which equates to a modulation scheme of 256-QAM 5/6, 80Mhz channel, Short Guard Interval, with a 3x3:3 adaptor.
However I would comment that the chances of you being able to effectively use 160MHz channels in a real-world environment are slim. There would need to be almost no other 5GHz Wi-Fi networks in use in your location for it to be worthwhile implementing.
The access point hardware does support 160MHz channels so your could try the Ruckus 'standalone' firmware to see if this allows you to use 160MHz. Unfortunately I've not been able to confirm this.