Frequently asked questions on car tyres.

How can I find my correct tyre size?

Please see the diagram below or if you have any further questions, please call us on 01494 797 820 or drop in as we are local.

How can I find out my tyre size?

Where can I find the correct pressure for my tyres?

You can usually find the manufacturer’s  recommended tyre pressure for your car on a sticker in the door jam, or in your owner’s manual. Some models have place the stickers on the fuel door or boot lid.

There are also many online guides to tyre pressure but it’s best to use your manufacturer’s guide.

Why is tyre pressure important?

Tyre pressure is very important for safety and fuel economy.
Correct tyre pressures are an important aspect for road safety and, by maintaining your tyres at their correct pressure, vehicle running costs will be minimised. Under-inflated tyres require more effort and wear more quickly.

What does the tyre labelling mean?

All new tyres come with labelling that identifies three key features:

 Fuel economy What is tyre labelling and what does it mean?

The diagram indicates how a tyre performs on fuel consumption. 
Fuel-efficiency is graded from A (most efficient) to G (least efficient).

Braking on wet roads

The graphic categorises a tyre on how well it brakes in wet conditions.
Graded from A (the safest, stopping in the shortest distances) down to G (least safe, with longest braking distances).

External noise level

This chart shows how well a tyre brakes in wet conditions.
Graded from A (the safest, stopping in the shortest distances) down to G (least safe, with longest braking distances).

What do tyre sidewall markings mean?

The tyre wall markings are mainly there for two reasons; firstly, to indicate the size and specifications of the tyre, and secondly, to What do the sidewall markings mean?prove that the tyre has passed European and other country safety standards.

We make it our business to know everything there is to know about tyres, and we can advise you on every aspect of tyre safety, specification and suitability. We stock a wide range of tyres to suit all budgets, and can supply and fit them for you whether you need replacement tyres locally.
Here, we’ve teamed up with the experts at Michelin to bring you a guide to tyre wall markings.

See the full  Guide To Tyre Wall Markings here

What does tyre speed rating mean?

How can I find out my tyre size?Tyre speed rating is the maximum speed for a correctly inflated tyre used under load. The speed rating is the letter at the end of the sidewall, after the load index number which indicates the maximum speed at which the tyre can carry the load corresponding to the Load Capacity Index. In this example, the symbol is V, therefore the maximum speed is 149mph or 240km/h. Common speed symbols in the UK are ‘S’, ‘T’, ‘H’, ‘V’, ‘W’ and ‘Y’

A tyre with a speed rating of V, for example, has a maximum speed of 240 km/h.

See the full Guide To Tyre Wall Markings here

What does RNF mean on a tyre?

RNF indicates that the tyre is reinforced. Reinforced tyres are for heavier vehicles and thus mostly fitted to vans, people carriers and some 4×4 vehicles and estate cars. Vehicles that carry heavy loads, are often fitted with tyres that are capable of supporting additional weight. These tyres are classified as EXTRA LOAD or XL or RNF (reinforced tyres).

See the full  Guide To Tyre Wall Markings here

What is the tyre load index ?

Load Index is a numerical code referring to the maximum load the tyre can carry at the speed indicated by its speed symbol. In this example, the code is 91, therefore the maximum load per tyre is 615kg.

See the table to find out specific load index details for each code:  Guide To Tyre Wall Markings

What does wheel alignment involve?

WHEEL ALIGNMENT – WHEEL TRACKING

Alignment or Tracking as it is sometimes known, can affect the handling and safety of your car and lead to excessive or uneven tyre wear. Wheel alignment can be upset by hitting a kerb, or hitting a pothole at speed. Alignment can also be affected by wear on steering or suspension components.

Why is wheel alignment important?

Wheel alignment is critical to steering, handling and tyre wear. Poor alignment can affect tyre wear and steering. Vehicle alignment is designed to minimise wear and tear and maximise comfort. Correct four wheel alignment will reduce wear on tyres, help increase their life and performance, and improve fuel economy.  It will also improve handling and driving safety by reducing steering and stability problems.

Why Have Your Wheel Alignment Checked?

  • Improve vehicle handling
  • Eliminate uneven tyre wear
  • Reduce premature tyre wear
  • Resolve pulling to one side

What causes irregular tyre wear?

Uneven tyre wear Uneven tyre wear can be caused by poor alignment, , worn suspension  or under improper inflation. There are several types of irregular wear. Most typical ones are heel and toe wear, one side wear, centre wear, braking flat spots. For all of them, there are different reasons why this wear happens. Regularly checking the tread depth and wear condition of each tire on your vehicle will let you know when it is time to replace a tyre or have the alignment checked.

Steering Geometry

Steering geometry problems are sometimes overlooked causes of tire wear. These problems can easily be avoided with the help of a thorough inspection.

More on Steering Geometry

Why causes my car pull to one side?

Steering Pulling to one side

Driving with steering pulling to one side can be tiring and can lead to serious accidents.  Pulling to one side could be caused by many things, from an underinflated tyre to failed suspension parts. One of the most common causes of pulling is Wheel Alignment.

Signs of poor alignment are:

  •  Abnormal or uneven tyre wear
  •  Pulling to one side while driving
  •  The steering wheel doesn’t return to its normal position after a turn
  •  The steering wheel is offset when driving in a straight line

Sometimes the solution is as straightforward as adding some air. Uneven air pressure is a very common reason for a vehicle to pull to one side. When the pressure in a tyre is lower on one side, the height of the tyre changes. This causes the wheel alignment to change.

More on Wheel alignment

Why do tyres wear unevenly?

Uneven tyre wear can affect the life and performance of your tyres, handling and safety. It’s important to spot signs of uneven tyre wear early and take remedial action.

Irregular wear can be caused by a number of factors including:

  • Loose or worn suspension components
  • Worn out or leaking steering parts
  • Uneven and incorrect tyre pressure
  • Wheels out of alignment

Irregular tyre wear can be caused by one or more problems, there are so many variables that there is no one single cause and you may not even notice them at all.

Worn steering components, such as loose ball joints, worn tie rod end, or excessive play in the rack and pinion mean that the tyres aren’t held at the correct angle and the overall geometry is affected. This might cause tyre scrub, where excess friction will quickly wear away the tyre tread.

Why does the Steering Wheel Vibrate?

Steering Wheel Vibration

Tyre Balance

One of the common reasons for car steering to shake is related to tyres.  If tyres not balanced properly it could lead to steering wheel vibration. This vibration starts at around 50-55 mph and become progressively worse to around 60 mph after which it might improve.

Alignment Problems. Drive on rough roads with lots of pothole can cause damage to the alignment set up which can lead to steering vibration. Steering that is out of alignment can cause the tyres to wear unevenly which might cause the steering to vibrate.

Wheel alignment

Wheel balancing should not be confused with wheel alignment which relates is to the direction and angle at which your tyres are se.

Faulty tyres

Vibration could also be caused by damaged or faulty tyres. Your tyres may need to be replaced if the tyres they are run with uneven wear.

How does wheel alignment affect tyre wear?

When wheels are misaligned, tyres wear unevenly relative to each other and within each tyre’s own tread. When tyres wear unevenly, their lifespan is shortened.

Typical wheel alignment is designed to minimise tyre wear and maximise driver and passenger comfort. Accurate four wheel alignment will reduce tyre wear and increase their life, performance, and fuel economy.  Correct wheel alignment will also improve handling and driving safety by reducing steering and stability problems.

Vehicle suspension misalignment can result in rapid, irregular tyre wear, which can lead to expensive problems, and can affect the handling and safety of your vehicle. If you notice any irregular wear on your tyres, you should have it checked by a professional as soon as possible. We recommend that you have your alignment or tracking checked every 10,000 miles or at least once a year, according to use and conditions.

More on Wheel Alignment

How do I know if my wheels need balancing?

Wheel balancing

If you wheels are not balanced correctly you will usually feel vibration in the steering wheel or throughout the vehicle.

What are signs of an unbalanced wheel

  • Vibration of your steering wheel or the whole car.
  • You might hear a humming and buzzing noise together with the vibration that increases with speed.
  • Tyre wear: a balanced wheel normally wears the tyre across the tread whereas an unbalanced tyre will wear along its edge.

Tyres might wear prematurely when the wheel isn’t balanced correctly. Even a small imbalance can , cause uneven tread wear and increased heat that shorten the life of the tire.

How do I know if my wheels need alignment?

Your wheels might need  alignment if you notice that your car  pulls sharply to the right or left travelling on a straight, flat road with no cross-wind. If your tyres wear unevenly, then your wheel alignment may require adjustment.

Familiar indications of wheels  poor wheel alignment:Wheel Alignment Blackboots Tyres Chesham

  • Pulling to the left or right.
  • Uneven or rapid tire wear.
  • Your steering wheel is skewed when driving straight.
  • Noisy or squealing tyres.

You should also have your wheel alignment checked if:

  • Your wheels hit something such as a kerb or pothole.
  • You experience steering or handling problems,
  • Your steering wheel does not return easily after a turn.
  • When you replace suspension or steering components.

What does four wheel alignment include?

Four Wheel AlignmentFOUR WHEEL ALIGNMENT

If you notice abnormal wear on your tyres, it’s often an indication of a mechanical anomaly with the vehicle, such as incorrect alignment, or problems with the steering or suspension mechanism. Vehicle suspension misalignment can result in rapid, irregular tyre wear, which can lead to expensive problems, and can affect the handling and safety of your vehicle. If you notice any irregular wear on your tyres, you should have it checked by a professional as soon as possible.

Four Wheel Alignment measures  14 primary alignment angles and compares them to the vehicle manufacturer’s alignment data. Wheel rim run-out compensation is taken into account, which gives accurate and repeatable readings. Four Wheel Alignment allows toe adjustments of individual wheels which ensure the steering wheel is properly aligned. Additional adjustments of other angles where necessary can ensure optimum performance and savings.

On modern cars, tracking alone is unlikely to deliver complete alignment or complete customer satisfaction.

More on Wheel Alignment

How many miles should I get from a set of tyres?

Tyre Lifespan

There is really no way to tell how long a tyre will last. The life and mileage of a tyre depends on a mixture of factors: its design, quality, driver’s behaviour, road conditions and basic maintenance. A set of tyres properly looked after and driven mainly on motorways can last much longer than poorly maintained tyres driven a city centre environment.

Key factors for Tyre Life

• The quality and construction of the tyre
• The road tyre and conditions
• Maintenance and driving driving style

However, tyre experts Michelin recommend that, after five years or more on your vehicle tyres should be inspected at least once a year by a professional. Then, If the tyres haven’t been replaced 10 years after their date of manufacture, Michelin recommends replacing them.

What is the minimum legal limit tread depth for tyres?

The legal limit for minimum depth of the tread on your tyres is 1.6 millimetres, across the central ¾ of the tread around the complete circumference of the tyre.
However, for optimum safety, most manufacturers recommend that your tyres are changed at 3mm.

Check the Michelin Care Guide on checking Tyre tread depth

How can I tell when my tyres need changing?

The legal limit for minimum depth of the tread on your tyres is 1.6 millimetres, across the central ¾ of the tread around the complete circumference of the tyre. When the tyre is worn to the legal limit the bars will be flush with the surface of the tread. Some manufacturers mould tread wear indicator bars into the tread grooves at regular intervals around the tyre to indicate when a tyre is worn to its limit of safety.

While that is the legal requirement some car manufacturers recommend you replace your tyres before they wear to that extent.

How often should my tyres be checked?

Check your tyre pressures at least once a month. Having the tyre correct pressure not only optimises the performance but also increases your driving safety. As a general rule you should check your tyres at least once a month, and before long journeys.

It’s important that basic checks are carried out regularly. A simple check can help you improve the fuel efficiency of your car and also avoid potential problems.

What is a run flat tyre?

Run Flat Tyres - BMW Run Flat ProblemsRun-flat tyres are designed to continue to be driven at reduced speeds for a short time after a puncture or other form of deflation.

They are fitted to many cars as standard. There is currently no standard code to identify  Run-flat tyres and different manufacturers use different symbols or letters. Check your owners manual to see if you have Run-flat tyres or call us for more information.

Read more about Run-flat tyres 

Can I drive with a ‘run flat’ tyre in a deflated condition?

Manufacturers of ‘runflat’ tyres or ‘ Self Supporting Tyres’  offer varying information but, as a general guide runflat tyres can continue deflated for up to 50 miles at speeds up to 50 MPH without interruption.

Run flat tyres were patented in 1892, improved and offered as an option in the 1990s mainly for sports cars with little room for spare tyres and jacks. These tyres have since become popular with manufacturers of high-end luxury cars, because of their safety and convenience.

The advantage of runflat tyres are:

Not having to change tyres in dangerous or awkward conditions.
In a puncture situation, run flats are more stable than conventional tyres.
Since they’re made to support your vehicle even when they contain no air, run flat tires will help you maintain better control in a complete air loss situation than conventional tires.

Check out the Michelin page on tyre basics

What is the penalty for unroadworthy tyres?

UK rules requires motorists to have a minimum 1.6mm of tread left over the central three quarters of their tyres. More than two-thirds of UK drivers don’t know the legal minimum tyre tread depth, according to new research.

Driving with an unroadworthy tyre carries a fine of up to £2,500 and three penalty points per tyre. So, if all four of your car’s tyres fall below the legal standard you could end up forking out £10,000.

Check out the Michelin page on tyre basics

When can you repair tyre punctures safely ?

If one of your tyres has a puncture, avoid driving on the tyre. Even if the puncture is a slow puncture, you should install the spare wheel in place of the affected wheel.

A tyre must be thoroughly inspected before repair and a repair must not be attempted in case of any of the following symptoms:

  1. Inadequate tread depth below the legal limit of 1.6mm across the tyre’s circumference.
  2. Splits, cuts, rubber crazing/cracking reaching the casing.
  3. Secondary effects, e.g. under-inflation/deflation damage or savaging by the point of a penetrating object.
  4. Worn out, aged or deteriorated rubber.
  5. Bead damage, including broken bead core
  6. Any sign of previous faulty repairs.

The BS AU 159 confirms that tyres repaired to this standard can operate at their original speed and load capabilities for the remaining life of the tyre. Furthermore, there are clear guidelines that dictate whether a tyre can be repaired to this standard. Before commencement consumers are advised to confirm with the Repairer that all repair work will be carried out in accordance with these BSI guidelines.

Do I need to fit winter tyres in the winter?

As the temperature drops, motorists will be contemplating if it’s worth shelling out for a set of winter tyres.

Winter tyres are not a legal requirement in the UK. But, if you live in an area that is prone to severe weather conditions, it is highly recommended to have winter tyres fitted.

Why should I change to winter tyres?

  • Normal tyres stiffen up when the temperature drops.
  • Winter tyres use a type of rubber (with a high silica content) and a tread pattern designed to stay flexible in low temperatures – below +7C – to give better braking and handling performance on snow and ice as well as on wet roads in cold conditions.
  • Winter tyres will be marked with a symbol showing a snowflake or snow-topped mountains

Read more on when should you run winter tyres?

How often do should I change my tyres?

As a safeguard, Michelin recommend that if tyres have not been replaced 10 years from their date of manufacture (see how to read a tyre sidewall), they should be replaced with new. Even if they appear to be in usable condition and have not worn down to the tread wear indicator.

Other reasons to replace your tyres:

  •  When your tyres worn down to the legal limit of wear
  •  If your tyre shows signs of aging
  •  If your tyre is damaged or If you get a puncture
  • If all your tyres or not the same specification or not suited to your vehicle