From left down to right down (ignore the memclock part at the bottom right)
As noted you already have some pretty lax timings, what I have listed above is basically the absolute most relaxed settings
without having to go to absolutely ridiculous settings like 3-5-5-12 or some crap...so basically when you hit your wall, that is the absolute wall
They key is basically the mind the sweet spot between latency and speed...so basically push your RAM to where you want it and then work your way back down tightening stuff back up from. I don't think you'll get much more than 285MHz though since you pretty much already have most influential settings incredibly loose
Generally you want the trc to be 2 faster than the trfc.
So if the trc is 7 the trfc should be 9, or the trc should be 16 since your trfc is 18. I'd try something like 12 for the trc and 14 for the trfc and see if that helps your RAM clock further.
I found that the formulas they gave over on dfi-street weren't really working out for me and I had to change things up and found there wasn't a set formula for determining much apart from cas + trcd + 0.5/1 = tras...the dudes running the OCZ tech support were giving me settings that didn't match that of what was listed at dfi-street either