Tyre Speed Rating Explained

In recent years there has been a huge growth in the number of different types of car available. From small, easy to park city cars to super-fast sports models, mud-plugging 4X4s to luxury SUVs, or small family saloons to 7-seater MPVs, there is something to suit everybody’s needs. However, all these different types of car have varying sizes, weight carrying and speed capabilities and therefore have a need for a particular tyre speed rating.

If you have ever looked at the side of the tyres on your car you will have noticed a large amount of numbers and symbols are printed there.

All of these say something about the tyres, and are important when you are selecting the correct tyres for your car.

Tyre Speed RatingThe most obvious marking is the size and tyre speed rating. This is always set out in a standard format, such as 225/60/R16 98H. The first sequence (225/60/R16) represents the dimensions and construction type of the tyre, which we will describe later. The second sequence (here 98H) represents the tyre load index (weight limit), 98, and the tyre speed rating, H. The load index is not a numerical value, but represents a position on a scale, so we will also discuss this later.

Firstly let’s deal with the tyre speed rating as it is very important that this is correct for the car on which the tyres are fitted.

ECE ApprovalECE ApprovalTyre SizeTyre Speed RatingWinter TyresLoad IndexTyre SizeLoad IndexTyre Speed RatingWinter Tyres

3d tire and alloy wheelWhich tyre speed rating should I choose?

There are currently 13 different tyre speed ratings, covering maximum speeds from 75 mph to 186 mph. The H mentioned above allows for a maximum speed of 130 mph. This rating is fairly standard on most family cars, as modern engine technology means that most 1.5 to 2.0 litre cars are easily capable of speeds above 110 mph.

Smaller city cars tend to have a tyre speed rating of T, which allows for a maximum top speed of 118 mph. On the other end of the scale, if you own a high speed sports model such as a Maserati or Ferrari you are expected to fit tyres with a rating of W (168 mph) or Y (186 mph). For real supercars, those that can exceed 186mph, specialist companies manufacture tyres with a tyre speed rating of Z, but this designation usually appears within the tyre size markings.

Speed RatingMiles/hour (mph)Kilometers/hour (kph)

Why do I need to choose the correct tyre speed rating?

We’ve mentioned that this rating is very important, and there are several reasons for this. The most important reason is safety. When travelling at high speed, it is fairly obvious that your wheels, and by extension your tyres, are turning much faster than at slow speeds. This generates more heat in the fabric of the tyre. If the tyre is run at a higher speed than its rated maximum it could be prone to catastrophic failure. Of course, this type of blow out might happen while you are still travelling at high speed, so the consequences are easy to imagine.

As a result of the safety implications of using the wrong tyre speed rating, many insurance companies state that insurance cover will be invalidated if tyres with the wrong rating are fitted.

As tyres with a higher tyre speed rating tend to be more expensive than those with a lower rating, people have argued that because there is a speed limit of 70 mph in the UK, then it is unnecessary to fit tyres rated to a much higher speed. It is also true that a car fitted with the wrong tyre speed rating is unlikely to fail its annual MOT test as long as it is in good condition. However in response, the insurance companies point out that the higher tyre speed rating also ensures that the tyres are able to deal with higher acceleration loads and the stresses of higher speed cornering, even if the maximum speed is not exceeded.

Question mark from stacked tire

Tyre Size Guide

Turning now to other information you can find on the side of your tyres, we mentioned earlier the tyre size and weight carrying markings. The marking we quoted, 225/60/R16, taken from the tyre on a 2004 Landrover Freelander, describes the physical dimensions of the tyre.

The first number, 225, is the width of the tyre tread between the sidewalls. It is expressed in millimetres and 225mm is just under 9 inches. Depending on the car, tyres are available from 115 mm (roughly 4.5 inches) wide, to 750 mm (nearly 30 inches) wide.

The second number, 60, is the height of the sidewall of the tyre, between the wheel rim and the tread. Just to confuse you, this is not expressed as a physical size in millimetres or inches, but it is the height of the sidewall as a percentage of the width of the tread. In our example, the height of the sidewall is 60% of the tread width of 225 mm, which means the height is 135 mm (about 5.3 inches). Tyres with a height of as low as 30% and as high as 80% are available. The lower numbers are known as low profile tyres, and are popular on sporting models, whereas the larger sidewall heights tend to be found on vehicles that ride higher on the road, such as SUVs and cars with off-road capabilities.

The final number, 16, is the size of the wheel rim the tyre is designed to fit, expressed in inches. Once you have worked your way between millimetres for the tread width, percentages for the sidewall height and inches for the wheel rim size, you eventually have an idea of the size of your tyre.

What does the letter R mean in the tyre size?

This does not concern the physical size of the tyre but refers to the construction type of the tyre carcass. The designator R stands for Radial construction, and most cars these days are fitted with radial tyres. You may occasionally see the letter B, for Bias Belt, or D, for Diagonal, but these are not very common for normal cars. If there is no letter shown, then the tyre is probably a cross-ply construction, but again these are not at all common.

Radial tyres were first introduced in 1946, and were a great improvement on existing tyres at the time. Radial construction means that the ply of the fabric starts at the bead of the tyre, which is the edge that fits on the wheel rim, runs up the sidewall, across the tread, and down the other sidewall to the bead on the opposite side. This type of construction means that the tyre flexes less under stress, allowing more of the tread to stay in contact with the road surface. This improves the tyre’s grip, particularly when cornering or under hard breaking, which in turn means safer driving.

As a bonus, this type of construction also reduces the amount of road imperfections that are transmitted to the car, resulting in a smoother, quieter and more comfortable journey.

What does Load Index mean?

The load index capacity is simply the amount of load that the tyre is designed to withstand. For example the figure 98, represents a point on a scale, in this case 750 kg. We have listed the most common numbers below, from 62 which represents 265 kg through a series of increments to 126, which is 1700 kg. However, this is not just the maximum weight of the car equally divided between the tyres. Most cars are heavier at the front end, as the tyres there are carrying the weight of the engine and transmission.

In addition, when a car is cornering, centrifugal force means that more of the weight of the car transfers to the wheels on the outside of the turn. If this weight exceeds the maximum weight loading of the tyre there is a risk that the sidewall will fail, with potentially very serious consequences. It is therefore very important that the weight rating of a tyre is suitable for the car to which it is fitted.

Load IndexLoad (kg) Load IndexLoad (kg) Load IndexLoad (kg)

Winter tyreWhat types of tyre are available?

Most tyres fitted to cars in the UK are suitable for all year round driving, and because of the temperate climate in the UK there are no specific requirements for separate tyres to be used in ice or snow conditions. This is unusual in Europe, as most other European countries have stringent requirements for cars to have tyres suitable for severe winter conditions, although they only have to be fitted in winter.

If your tyre has a marking M+S, (which stands for Mud and Snow), or a symbol that looks like a mountain with a snowflake inside it (known as a tri-peak), this means that the tyre is a winter tyre, designed to maintain its grip and traction in severe weather conditions.

As a side note, it is generally acceptable to fit winter tyres that have a one grade lower tyre speed rating than standard tyres. This means that if your car normally runs on H rated tyres you can legitimately use U rated winter tyres.  You should however always check that your insurer allows this.

What about other tyre markings?

There are a number of other markings you will find on the side of a tyre. Due to the multinational style of tyre manufacture and sales some of the markings are required by other governments, particularly the USA, and have no relevance to the UK. However, other markings are very important, both in the UK and worldwide.

EU Tyre LabelAll tyres sold in the UK, and in Europe are required to carry an ECE marking, which confirms that the construction of the tyre conforms to European standards, as well as an EEC Noise Approval marking, which means that the tyre conforms to European noise reduction standards. There will also be a stamp which confirms the date of manufacture of the tyre.

Additionally since November 2012, all tyres in Europe must carry an EU tyre label.  This label was introduced to make it easier for buyers to compare different tyres.  The label shows ratings for fuel efficiency, wet grip braking performance and exterior noise levels.

Due to variations in tread design, some tyres need to be fitted so the tread operates in a certain direction, or even on only one side of the car. Where necessary this information is indicated on the tyre by an arrow, showing the direction of rotation, and the words “outside” and “inside” on the respective sidewalls.

All of these markings are standardised across Europe, thanks to the efforts of the European Tyre and Rim Technical Organisation (ETRTO). ETRTO is an organisation which has operated for fifty years to help bring different national standards into alignment, and to promote the sharing of good practice between manufacturers.