What can be the effect of an overload of only 20%?

The correct combination includes all three points because an overload, even by 20%, can significantly impact vehicle performance and safety.

1. **The brakes may be overstrained**: Excess weight means that more force is needed to stop the vehicle, which can lead to overheating and potential brake failure.

2. **Steering may become worse**: Increased load can alter the center of gravity and weight distribution, making steering less responsive and harder to control, especially in turns.

3. **There may be too much strain on the load-bearing parts of the vehicle**: Components like the suspension, axle, and tires are designed to handle specific weights. Exceeding these limits can lead to faster wear and potential failure.

According to German traffic regulations, maintaining the correct load is crucial for safety and compliance, ensuring that vehicles operate within their designed specifications.