If you can't take 160kts to 4nm tell the controller that, and do it early. This is not rocket science. The EK stability criteria is +20kts at 1000' IMC. A lot of the time 160kts is even within this margin.
To say you can fly the speed required and not do so is just irresponsible. To tell the controller at 10 to 8nm you can't do this does not give him much chance to space the guy behind you. You know what the limit is, if on the day you can't do it, tell the controller what you can do early, 160kts to 5 or 6nm perhaps.