The steering wheel becomes stiff gradually over time.
Car Problem Diagnosis
Same with other mechanical parts, steering gears and linkages are also lubricated with grease to reduce the friction between those parts making the steering of the car much easier. Since the problem gradually occur over a period of time, it is safe to say that the lubrication for the steering system has been loss. However, another cause of this kind of problem involves underinflated front tire, if the front tires does not have enough air stiff steering wheel can be felt by the driver.
Possible Cause of Stiff Steering Wheel
Not enough or loss lubrication on steering wheel gears or linkages.
How to Fix Stiff Steering Wheels
Bring the car to a reputable auto repair shop and ask the mechanic to lubricate the steering gears and linkages to fix the problem. Often times it is necessary to replace lubrication seals because it was damage, causing the loss of lubrication on the steering system.