This error has been present in the real virtuality engine from since its first iteration(though i understand wheels did work in one iteration i forget the name of i think)to my knowledge. a small fact, the noticeable deadzone will change size mostly based on your wheels particular range of motion in real life, so a wheel that turns only 90 degrees either side will probably experience a 20-30 degree deadzone left and right whereas more expensive wheels that have a 900 degree range of motion will experience much larger dead zones, pretty much all the time it is a 90 degree deadzone for 900 degree wheels.
this must be fixed by the addition of a properly coded single axis analog input like the thrust analog input, for devices like the wheels. this is all in the name of boosted gameplay experience with the added realism of a steering wheel, therefor i believe it is an essential that the devs cater to their more passionate fans who want to use multiple peripherals with the maximum success ingame.