From Michelin
Below, we list six major reasons why you should seriously consider changing your tyres.
In certain situations, a tyre can be repaired. However, the repair of Michelin tyres must be preceded by a careful examination of all areas of the tyre, inside and out, by a trained specialist.
The removal of the tyre from the wheel is essential because internal damage is not visible while the tyre is fitted.

Infinity Tyres
  1. If you get a puncture

Modern tyres are very sturdy and can cope with most things. Punctures, though, can and do still happen.
A tyre specialist should check your tyre after a puncture to decide whether it can be repaired.
Safety procedures when you have a puncture while on the move:
Always consider your safety and that of your passengers, pull off the road in a safe place, Put on the parking brake Switch off the engine and put the car in a low gear (or in Park on automatics), Switch on your hazard warning lights, Wear a yellow high-visibility vest, Place a warning triangle at the side of the road 100m behind the car because your safety comes first – always!
Helpful tips for changing a punctured wheel
* DO NOT attempt to change a wheel if it risks the safety of you or your passengers.
* Carry a pair of sturdy gloves
* Carry a bin bag in your boot, in case the tyre you’re removing is covered in mud!
* Carry a sturdy board to place your jack on in case the ground is soft, to avoid the jack sinking in.
* Where necessary, use a light machine oil on the wheel nut threads to help their removal.
* Check the inflation pressure of the spare tyre before fitting. If this is not possible, once fitted drive carefully at low speed until it can be checked.
Visit the nearest service station and inflate the tyre correctly.
* Badly tightened wheel nuts risk damage to the brake discs or wheel mounting system.
* Use a torque wrench to make sure you tighten the nuts correctly with the correct torque.
* If you don’t have a torque wrench get a tyre specialist to check them as soon as possible.
This will ensure the correct torque has been applied.
Correctly tightened wheelnuts will also make it easy to remove them.

  1. When your tyres worn down to the legal limit of wear

It’s a good idea to check your tyres regularly for tyre wear. But how?
Here’s a simple way to tell if your tyres are worn out.
A Michelin man figure on the shoulder of a Michelin tyre shows the location of the tread wear indicators situated in each of the main grooves of the tread. These indicators are small raised areas at the bottom of the grooves of the tread pattern.
If the surface of the tread rubber is level with these raised areas, the tyre tread depth is most likely very close to the legal limit of 1.6 mm. Beyond this limit, you are putting your safety at risk and you are breaking the law.
Even if the remaining tread depth is greater than 1.6 mm, you should adapt your speed and driving style to the external conditions, particularly on wet roads.
Winter tread wear indicators at 4 mm (only in some European countries)
The intermediary tread wear indicator indicates a remaining tread depth of 4 mm. Thanks to MICHELIN 3D sipes on the full tread depth, the tyre maintains its winter performance below this indicator.

  1. If your tyre shows signs of aging

Tyres have no predictable life. It does’t matter when the tyres were made. Tyres age even when not used, or if only used occasionally. There are many factors that will affect the life of the tyre such as temperature, maintenance, conditions of storage and use, load, speed, pressure as well as driving style. These will have a great impact on the length of service life you can expect from your tyres.
Pay regular attention to your tyres for these reasons:
Michelin recommends that all drivers pay regular attention to the external appearance of their tyres for clear signs of aging or fatigue.
This can include cracking of the rubber or deformation, etc.
Excessive aging of tyres may lead to loss of grip.
Michelin also recommends all tyres, including the spare, are inspected regularly by a tyre specialist. They can tell you whether your tyres should continue in service.
How old is too old? The five year test, after five years or more in service, your tyres should be thoroughly inspected at least once per year. If the need arises, follow the recommendations of the vehicle manufacturer regarding replacing the original equipment tyres. As a precaution, if the tyres have not been replaced 10 years from their date of manufacture (see how to read a tyre sidewall):
Michelin recommends replacing them with new tyres. Even if they appear to be in usable condition and have not worn down to the tread wear indicator.

  1. If your tyre is damaged

Your tyre can be seriously damaged if it impacts any solid object on the road, like a kerb, pothole, or sharp object. Any visible perforation, cut or deformation must be checked thoroughly by a tyre professional. Only they can tell you whether the tyre can be repaired or has to be changed. Never use damaged tyres or tyres that have run flat or at very low pressures unless they have been thoroughly examined internally and externally by a tyre professional. Inspection by a professional is absolutely necessary because internal damage is not visible while the tyre is mounted; only then can a decision be made as to whether the tyre can be out back into service,
Leave it to the experts
A tyre specialist will tell you if your tyre can be repaired after damage has occurred.

  1. If you identify abnormal wear

Abnormal, uneven tyre wear in patches, in the centre, at the edges may indicate a mechanical problem like improper wheel alignment, or a problem with wheel balance, suspension or transmission. It could also be that you’re driving with the wrong tyre pressure. If you notice abnormal wear, contact your tyre specialist.
To prevent uneven wear, have your wheels aligned and balanced by a tyre specialist. This will also extend tread life and give you a smoother ride. Another way to keep your tyre wear even is to regularly rotate your wheel positions.
Common causes of abnormal tyre wear:#
* Wear on one shoulder: suspension misalignment.
* Wear on both shoulders: under-inflated tyre.
* Wear along the tyre’s centre: over inflation.

  1. If they’re not suited to your vehicle

For best all-around performance, the same type of tyre should be used in all four wheel positions. Tyres of different sizes, constructions, and stages of wear may affect vehicle handling and stability.
In addition, there may be specific recommendations by vehicle or tyre manufacturers which may apply to your vehicle.
These should be followed:
* please check your vehicle handbook for details.
* Do not mix radial and non-radial (i.e. cross-ply or bias-belted) tyres on a vehicle. If mixing tyres is unavoidable, never mix radial and non-radial tyres on the same axle. If two radial and two non-radial tyres are installed on a vehicle, the two radials must be installed on the rear axle and the two non-radials on the front axle.