I use old MS SW Forcefeedback Wheel and pedals (gas pedal spring has weakened a lot since I started driving with RT). In the input.ini file I have the default values:
SteeringExponent=1.0; ThrottleExponent=1.0; BrakeExponent=1.0;
And ingame race steering settings I use always slowest (left) with all cars. In Rally Trophy's controller settings I use deadzone setting value 7 steps from left (25-35%), sensitivity fully left (0%), force level max (100%). This ingame steering settings are originally made by Rauno Aaltonen and he told these settings in some news paper article that was also mentioned (in JoWooD Rally Trophy forums). The Rauno Aaltonen settings took so called steering bug away from my PC, so it really works well. I have used these settings about from the beginning of the year 2002. Actually RT's deadzone is not a real deadzone, the car turns a bit even with smallest turns you make. With the above steering settings the wheel in the RT cockpit view turns same amount as my MS SWFFB Wheel, which looks and feels nice (why this was not the default setting?). Thisway the steering is much like normal car - slow, but accurate. And the steering speed is about same in the whole steering area, so no different speeds in different wheel positions as 1.0 version is with default settings (aka steering bug).
These settings feel still a bit faster than my own car (feel nearly as fast as go-kart steering speed for me). Because the MS Wheel cannot be turned as much as real car's wheel (it has same amount of turning as go/kart cars), it can never feel as my own car. Or I would lose very much of the turning angle (couldn't drive in hairpins then).
If you want to set REAL deadzone to your steering in Rally Trophy, you need to use your controller setup or DXTweak2 (I use this). The real deadzone is area where the tyres does not turn at all when you turn wheel. I use 3% setting with DXTweak2 to my wheel to get vibration away, when the wheel is in the middle (my wheel has weared or it is just a bit inaccurate in the middle). If I set deadzone to 0% (5% was default), it is not possible (or it is very hard) to drive straight without turning wheel all the time from left to right and back. Eventually car goes straight, but makes small turns from left to right all the time itself. With this small real deadzone, you remove controller inaccuracy and make some force effects smaller (to make driving more accurate) when the wheel is in the middle (you drive straight). The car follows road like real car does and makes those small turnings without giving too much notices to the wheel. I recommend that the real deadzone is as small as possible (just for removing calibration or controller inaccuracy), to keep driving realistic (as car in good condition).
If the wheel vibrates too much (wheel makes fast turning between left and right), when car is in neutral gear, you can test if you like it more without forces at all. But if you set the real deadzone too wide, you lose realistic feeling and touch to the road. And as I said above, the Rally Trophy internal deadzone is not same as this real deadzone setting (the Rauno Aaltonen setting I use is still at the 1/3 from left).
My own car is Ford Granada 2.5 GL Diesel (1983). The power steering has been removed (the wheel is original small that was used with power steering). So the steering is HEAVY and SLOW in my own car (slower than steering in RT with above settings). And this steering in my car is in good shape (like new). The cars in RT (or in your car) may have better handling and faster steering than my car, but as I don't know any of those RT cars in reality, I just have to set comfortable settings. Set your steering like your real car, then the driving feels more realistic (but G-forces are still missing, though). Well, atleast set steering settings so, that you can drive as you want. I want to drive without errors and easy as possible, so I set the steering to be close to my own car.
I have driven once with huge deadzone in real car (well the car was not in good condition). See article here.