We place an enormous amount of trust in the tyres we drive around on – we literally place the entire weight of our vehicles on them after all. Ensuring that these invaluable hoops of rubber remain safe to drive on is imperative: the information in this guide will help you make informed decisions about when to change, how to change and how to avoid having to change your tyres.
In our tyre classification guide we cover many topics that are a useful accompaniment to the issues in this section: whereas we deal with when and how to change a tyre here, the classification guide deals with what you want to change your tyres to.
With clear laws about tread depth and tyre damage (see below for the latter), it’s important to emphasise that these limits represent the extremes of wear and that you should consider changing well before wear and damage become an issue.
Changing tyres has traditionally been part of routine maintenance for two reasons:
The former reason applies less to UK motorists because of the nature of our weather. The latter is now disputed: instead of promoting even wear, some suggest that you should put your worst tread on the front of the car and that it’s best to buy new rears rather than swapping partially worn front tyres to the back.
Simple 'end of life' wear is not the only reason for changing a tyre. Here are some common examples of causes and consequences that will force you to change:
Cuts are relatively common and can occur as a result of driving over sharp objects on the road. In UK law, a tyre with a cut in excess of 25mm must be replaced. Any cut that exposes the ply or cord is also illegal – in both cases, there is an increased risk of blowout.
Hitting a curb or another obstacle can sometimes cause damage to the casing, either in the form of a cut or bulge. Again, these are a blowout risk.
In suspension terms, ‘camber’ refers to the angling of wheels away from the axle. Some set-ups can improve handling, however, tilting wheels in this way tends to cause rapid wear on the edge of the wheel that makes contact with the road.
Under-inflation causes the outer edges to take the load and thus wear more quickly than the centre.
When filled with too much air, a tyre becomes too rounded, causing the middle to extrude and take the entire weight of the car.
At high speed, an emergency stop can cause massive friction resulting in rapid wear, potentially to the extent that the tyre punctures and deflates. For this reason, you should always check your tyres at the nearest safe opportunity after performing an emergency stop.
Whereas camber configuration may be desirable, plain old misalignment (where the front wheels are pointed at slightly different angles) rarely results in a better drive, and can cause some rapid wear and feathering on the tread.
Images used courtesy of Kwik-Fit
Park your vehicle on level ground as far away from traffic as possible. If it's dark, ensure that you are wearing a high-visibility jacket and using a torch. If near traffic, turn on your hazard lights. Any passengers should also get out of the car, and any heavy luggage will need to be removed.
Remove any wheel cover or centre cap to gain access to the wheel nuts, and give each one a ½ turn with your wheel wrench. Then place your jack under the jacking point nearest the wheel – these points vary from vehicle to vehicle and will be indicated in your owner’s manual, so it’s important to know where they are ahead of time. Failure to place the jack properly can cause damage to the car and may provide an unstable lift. Turn the jack handle clockwise until you have raised the wheel completely off the ground. Remove the wheel nuts and remove the tyre.
Lift the replacement up onto the mounting surface and tighten all of the wheel nuts with your fingers. To ensure perfect alignment, you should tighten the nuts further (but not fully) in the order shown in the image - if drawn out, the order looks like a five pointed star.
Lower the car by turning the jack handle anti-clockwise until the wheel is resting on the ground and the jack can be removed. Give those nuts a last turn (using the same pattern above) to ensure everything is secure, and make sure you pack everything back into the vehicle.
The only thing that’s easier to follow than a step-by-step guide is a video of a step-by-step guide. Check out the entire process in the video below.
It is far less common nowadays to be given a full-sized spare that functions as effectively as your main tyres. For space and weight reasons you may have a mini spare (otherwise known as a ‘space saver’), which is good enough to get you home but unsuitable for continued use. Such equipment should not be used to drive above 50mph.
You can find a summary of how to change a tyre on our official Slideshare here
Flat tyres are, to a certain degree, unavoidable. Nevertheless, good maintenance practice and sensible driving decisions should reduce the risk of punctures and blowouts.
Underinflated tyres are a blowout risk because of the increased friction and heat they encounter. Overinflated tyres are more likely to pick up damage from potholes and bumpy roads. Checking your pressure at least once a month could prevent either scenario.