There are two types of deadzone when it comes to FFB wheels.
Steering deadzone: This means that around the center, you move the wheel -> nothing happens in game. This leads to a wandering effect on the straights, because at the center you have to rely on visual clues only to know if you're going straight (instead of relying on the wheel feel).
FFB deadzone: This means that the game is signalling the wheel to move -> wheel doesn't move. E.g. the FFB signal from the game can tell the wheel to move at 0-100% strength. So let's say your FFB deadzone is 10%, a small bump/kerb (telling the wheel to move at 9% for example) will not be felt in the wheel. This also affects center wheel behavior, because usually the forces keeping the wheel centered are relatively weak.
Steering deadzone can be corrected by using the corresponding slider in the wheel's configuration settings. Should be already at 0% if I recall correctly.
FFB deadzone (or minimum input as it's called in other sims) is in the 'FFB calibration' screen. The value to input there depends on your wheel. On PC there's a tool called WheelCheck that can check it for you.
On console it requires a bit of trial and error, but it's fairly easy to do. If the value you put in is too high, you will get oscillation on straights/standstill (when not holding the brake). This is the result of the FFB motors working against each other. So you want to test up until you get oscillation, then dial it back a notch until it's gone and you will have your value. Start at a low value! High values can damage your wheel! Start at something like 0.05, then tone up and down from there.