While standard tyres are designed for most daily purposes, reinforced tyres are constructed for more specific needs: they need to cope with greater load pressure. See when to use reinforced tyres and what are their advantages and disadvantages.
What are reinforced tyres?
Every tyre size has a specified tyre load index. This value is strictly defined by technical organisations that gather tyre manufacturers such as ETRTO (European Tyre and Rim Technical Organisation). Reinforced tyres are adapted to loads and pressures bigger than those provided for the standard version of a given size. They have been designed for any scenarios when the tyre’s use requires additional, higher than the standard load capacity.
Designation of reinforced tyres
Typical tyre markings for reinforced tyres are as follows:
Extra Load (XL)
Less common labels include EXL, RFD and RF. The most popular mark at present is XL, which is replacing the other tyre labels found on products launched a few years ago.
How do reinforced tyres differ from standard tyres?
A tyre with the basic load capacity defined for its size is called an SL (Standard Load) tyre. The difference between a reinforced tyre (XL) and an SL tyre is that the XL tyre meets the standard requirements for its size and, at the same time, offers the possibility of using higher tyre pressure. It consequently has an increased load capacity.
From the outside, reinforced and standard tyres look exactly the same – you can’t see the differences. A tyre’s load index is increased by modifying its face (the part under the tread) or heel. Such modification may involve using higher-strength materials, reinforcing the principal elements of the tyre, or using additional elements. Solutions used to increase the load index include applying an additional carcass layer.
What are the characteristics of reinforced tyres?
Tyres with the XL marking have a greater load capacity, because the design makes it possible for higher air pressure to be maintained within the tyre. The maximum load permitted on a wheel is always related to the pressure. If the vehicle is certified for use with reinforced tyres, information about the recommended pressure will be given in the manual.
The table below shows the pressure values used in the wheel and the corresponding values of the permissible load. The size 205/55 R16 was used as an example. By default, it has a load capacity index of 91, which allows a maximum load of 615 kg per wheel. XL versions of this size usually have an index of 94, which increases the maximum load per wheel to 670 kg.
Table of dependencies between pressure and load on size 205/55R16:
Higher load capacity of the tyre increases durability to high speeds. Therefore, when there are several speed indexes in a given size and tyre model, the XL marking will be associated with the tyre of the highest speed rating.
C-type reinforced tyres are designed for delivery vehicles and are characterised by a high load index and a lower speed index. C-type tyres or reinforced delivery tyres can be used in cars with a maximum load of 3.5 tonnes.
The advantages of XL tyres
Thanks to their increased load capacity, reinforced tyres offer many advantages:
- When normal and reinforced tyres are used in the same way, the latter will last longer. XL tyres can travel for a greater total distance without suffering internal damage, even when under intensive use. However, this applies only if you follow the car manufacturer’s recommendations as for the right tyre pressure.
- Reinforcement of the tyre improves resistance to mechanical damage that can result from, for example, driving at high speeds into the curb.
- Better traction and adhesion properties. The tyre’s greater rigidity ensures stability, more effective transmission of the vehicle’s power to the road surface, better handling on corners, a faster reaction to turns and a greater resistance to additional loads and forces (acceleration, braking, centrifugal forces on turns).
The disadvantages of XL tyres
There is no such a thing as a perfect tyre. All models are a designed and calculated compromise between various parameters and this applies to reinforced tyres as well. The typical cons of reinforced tyres are:
- Higher noise levels. The tyre certification requirements permit reinforced tyres to produce 1 dB (decibel) more noise than normal tyres.
- The use of reinforcement may involve increasing the thickness of the face (under the tread) and shoulder of the tyre. This, in turn, can cause increased rolling resistance and greater fuel consumption.
- Reinforcement usually involves an increase in the tyre’s weight and mass, which again leads to higher fuel consumption.
- Modifications may lead to a lowering of driving comfort, when compared to using normal tyres (however, such differences will be minimal and rarely felt by the driver).
Reinforced tyres have both advantages and disadvantages.
XL Tyres – are they worth buying?
Any information concerning the need to use XL tyres will usually be found in the vehicle’s manual. This may often apply in the case of vans, large saloons, estate cars and delivery vehicles. Reinforced tyres are also often used in high-performance sports cars.
If the vehicle manufacturer has gained certification for the vehicle running on reinforced tyres, then it is unconditionally necessary to comply with that requirement. Buying car tyres with a standard load index because they are cheaper than XL tyres is a breach of safety conditions and can have unpleasant consequences (such as insurance companies may refuse to cover the costs in the case of an accident).
It is a good idea to buy reinforced tyres if:
- You often travel with a significant load: in this case, using them may improve the lifetime of your tyres.
- You have a vehicle with a powerful engine: XL tyres will then provide greater stability on corners and a better reaction to both acceleration and braking at high speed.