Steering wheel knobs – commonly known as spinner knobs or Brodie knobs – have long been used to make steering easier and more efficient. They are particularly beneficial for drivers with limited mobility, but many motorists also use them to make manoeuvring easier when parking or driving at low speeds.

Despite their practical benefits, there is often confusion surrounding their legality and how they affect a vehicle’s MOT test. Many drivers worry that fitting a steering wheel knob could automatically result in an MOT failure. In reality, the situation is far more straightforward.

This guide explains how steering wheel knobs are assessed during an MOT inspection, what the DVSA regulations say, and the common issues that could lead to a failure.

Are Steering Wheel Knobs Legal in the UK?

One of the most persistent myths among UK motorists is that steering wheel knobs are illegal. Fortunately, this is not true.

There is currently no UK law that specifically prohibits the use of steering wheel knobs. Neither the Driver and Vehicle Licensing Agency (DVLA) nor the Driver and Vehicle Standards Agency (DVSA) bans their fitting to a vehicle.

These devices are commonly used as mobility aids, helping drivers steer with one hand while maintaining control of the vehicle. However, their use is not limited to disabled motorists. Any driver may use a steering wheel knob provided it does not compromise vehicle safety or steering performance.

How MOT Testers Assess Steering Wheel Knobs

During an MOT inspection, the steering wheel knob itself is not a testable item. Instead, MOT testers focus on the condition and safety of the steering system and steering wheel.

The primary concern is whether the knob has caused damage or created a safety issue that could affect the vehicle’s roadworthiness.

Steering Wheel Condition

The steering wheel must remain structurally sound and safe to use. Testers will carefully inspect the wheel for any signs of damage, particularly around the area where the knob is attached.

Common concerns include:

• Cracks or splits in the steering wheel rim
• Distortion caused by excessive clamping pressure
• Excessive wear around the mounting point
• Damage that affects the driver’s grip or control

If a steering wheel knob has caused significant deterioration or weakened the steering wheel, the vehicle may fail its MOT.

Secure Attachment

A steering wheel knob should be securely fitted and free from excessive movement.

A loose or poorly mounted knob could interfere with steering control and potentially become detached while driving. Although the knob itself is not inspected as a separate item, any safety risk resulting from its installation may be considered during the test.

Sharp Edges and Protrusions

Testers also assess whether any part of the steering wheel or attached accessories presents a potential injury risk.

A steering wheel knob could raise concerns if it:

• Has sharp or jagged edges
• Creates dangerous protrusions
• Contains broken or damaged components
• Increases the likelihood of injury during a collision

Safety remains a key factor in all MOT inspections.

What the DVSA MOT Manual Says

The relevant guidance can be found within Section 2: Steering of the DVSA MOT Inspection Manual.

Although steering wheel knobs are not specifically mentioned, the manual requires that steering wheels must:

• Be in satisfactory condition
• Be free from excessive damage or deterioration
• Provide adequate strength and structural integrity
• Remain securely attached to the steering column

As a result, any damage caused by the installation or use of a steering wheel knob may be assessed under these existing steering regulations.

In simple terms, the knob is not the issue—the condition of the steering wheel is.

Common Reasons a Vehicle May Fail

Damage to the Steering Wheel Rim

This is the most common MOT-related problem associated with steering wheel knobs.

Some clamps apply excessive pressure to the wheel, especially if they are poorly designed or incorrectly installed. Over time, this can result in:

• Cracked steering wheel coverings
• Structural weakening of the wheel rim
• Distortion of the steering wheel
• Sharp edges caused by worn materials

Any damage that affects safety or control could lead to an MOT failure.

Impaired Steering Control

Although relatively uncommon, a steering wheel knob could contribute to a failure if it interferes with normal vehicle operation.

Examples include:

• Restricting hand placement on the steering wheel
• Obstructing access to indicators or controls
• Limiting steering movement
• Creating a distraction during the operation

A driver must maintain full and safe control of the vehicle at all times.

Poor Installation

Improperly fitted steering wheel knobs can create several safety concerns.

A tester may identify issues if the knob:

• Moves excessively during use
• Appears insecurely attached
• Has been fitted using unsafe modifications
• Shows signs of potential detachment

Professional installation is often the best way to ensure compliance and long-term safety.

How to Avoid MOT Problems

Choose a Quality Product

Not all steering wheel knobs are manufactured to the same standard.

Look for products that feature:

• Robust construction
• Smooth, rounded edges
• Protective rubber inserts
• Secure but non-damaging mounting systems

Investing in a high-quality product can significantly reduce the risk of steering wheel damage.

Consider Professional Installation

Although many steering wheel knobs are marketed as DIY accessories, professional fitting can help ensure they are installed correctly and safely.

This can also prevent overtightening, which is one of the leading causes of steering wheel damage.

Carry Out Regular Inspections

Drivers should routinely check:

• The steering wheel for cracks or wear
• The mounting point for signs of damage
• The knob’s security and stability
• Any sharp edges or loose components

Addressing small issues early can prevent costly repairs and potential MOT failures later.

Final Verdict

Steering wheel knobs are legal in the UK and do not automatically result in an MOT failure. In fact, they can be valuable driving aids for many motorists.

However, MOT testers will assess the overall condition and safety of the steering wheel and steering system. If a steering wheel knob causes damage, creates a hazard, or affects vehicle control, the resulting defect could lead to a failed test.

By selecting a quality product, ensuring proper installation, and regularly inspecting both the knob and steering wheel, drivers can safely benefit from this accessory while remaining fully compliant with MOT requirements and UK road safety standards.

This version is more suitable for publication on a motoring website, garage blog, or automotive advice platform, with stronger SEO targeting around terms such as “steering wheel knob MOT”, “spinner knob legality UK”, and “MOT steering wheel regulations”.