What is Tyre Runout

When a tyre is not perfectly circular, it can become imbalanced. While this tends not to affect the performance of a vehicle in its beginning stages, if left unmanaged it can lead to problems such as excessive wear and vibration.

This is known as tyre runout, otherwise known as “out-of-round”. Often confused with poor tracking, this issue can lead to steering and control issues with your vehicle. There are two main types of runout in tyres, the first being radial (the more common of the two), the second being lateral runout.

Radial Runout

Radial runout relates to the distance between the centre of the wheel and the tread on the tyre, which should be equal in distance all the way around. This type of runout creates discrepancies in distance from one point to another on the wheel.

The greater these are, the more likely the wheel is to bounce as it rotates. This can cause vibrations that frequently move up the steering column, which can be felt by those inside the vehicle.

Lateral Runout

Lateral runout involves the distance between the edge of the tyre tread and the centre of the wheel. The more lateral runout there is, the less supported the tyre will be at certain points as it rotates.

This can cause the vehicle to vibrate, wobble or even lose control of movement, causing it to shift from left to right randomly (almost like a broken shopping trolley).

Preventing Tyre Runout

As a preventative measure, taking your vehicle to a trained mechanic in the first instance can help to prevent runout from happening in the first place.

Other preventative measures include having your tyres maintained rotated and inspected by a trained professional regularly.

Causes of Tyre Runout

Runout can have a number of root causes. In some cases, it can be due to bumpy terrain or even collisions.

Other causes include manufacturing issues frequently involving cheaply-made tyres not constructed in line with quality control protocols, or wheels made using low-grade moulds (high-quality tyres should be constructed with segmented moulds).

Other factors leading to runout include improper seating - rather than the actual seats inside the vehicle, this refers to a piece of rubber tubing called a bead seating ring.

This is intended to fit over the wheel, closing the gap between the tyre bead and the rim to allow for ease of inflation. When this is not properly lubricated, the ring may lose slippage, which can lead to incorrect mounting.

Checking Pressure and Condition

Another proactive measure you can take to prevent runout is to regularly check the tyre pressure. Always check your tyres when they are cold, as exterior temperatures can cause the tyre to expand, affecting its “true” pressure levels.

Checking tyre condition is also a good habit to develop: the thickness of the tread on standard tyres should be a minimum of 1.6mm in a continual band across the middle three-quarters of the width of the tread - and should adobe rebound for the entirety of the circumference.

Wear Indicators

Most modern tyres have what are known as “wear indicators''. These raised bumps positioned around the circumference of the tread (in between the grooves) are there so that when the tyre wears down to the level of the bumps, it is time for a replacement.

If this is the case, you may want to consider fitting new tyres on the rear, as opposed to the front wheels. This is because the best tread is available on the back wheels of the car - in slippery or wet conditions, this will be the part that slides away first - so it’s important to ensure maximum grip here.

Checking the Tyres

To diagnose runout, check your tyres for flat-spotting. This is (as the name suggests) a flat spot on the tyre where it has been in contact with the ground for a period of time.

If you have identified this, you can either use a dial indicator or runout gauge, which will help confirm whether there is a balance issue.

How to Check for Tyre Runout

When checking for runout on your tyres, look for coloured lines that run the circumference of your tread on a new tyre. While some of these are intended to give tyre distributors information about the tyre, one of them (typically the red or blue line) is the runout indicator, usually situated to the right to left of the tread.

The closer this is to the central line, the straighter the tyre will be. Distance from the middle shows the degree of runout. Ideally, new tyres should have two runout lines roughly the same degree front eh middle, but on opposite sides of the centre so that they cancel each other out, resulting in straight steering.

How to Fix Runout on a Tyre

Wheels can be re-balanced either dynamically or statically, using wheel weights to adjust the static balance of the wheel and stopping it from wobbling. When a wheel is dynamically balanced it is also statically balanced - however the reverse does not apply.

Since tyre runout is considered a self-propagating issue, the problem is likely to worsen unless addressed - so if you notice signs of runout, it’s important to have your vehicle checked by a trained mechanic as soon as possible.

 If your vehicle has suspected runout, contact our trained and experienced tyre Manchester specialists today who can help to diagnose and resolve the issue.