As my 10 year old Kumhos on the rear were past the wear indicators I thought I had better find something legal to get around on. After a lot of research I ended up getting some Federal RS-RR's. They only come in 255 40 17, however they are sized a bit larger. The old 275 40 17s were pretty much exactly 275 width on my 9.5" rims. The 255 40 17's RS-RR's are about 267, so not a lot narrower. They are 15mm smaller diameter but I can live with that.
The tread pattern is awful, something only a ricer would love and they are noisey - someone said they sound a bit like your being followed by a jet, and that is about right. Not a big deal in our cars though and I dont think you would notice in an open car.
But, they are terrific value and the reviews I have read have been very positive on the grip. Treadwear is stated at 140. Initial impression is that it is much harder to break traction than the Kumhos, but, as I said they were very old. If they go OK, Ill get a couple for the front before nats (The 235's size around 245+ apparently). The Kumhos on the front have plenty of tread at the moment. Not sure why the rears have worn more quickly
A few pics:
