Tyres for lorries, HGVs and buses: the answers

315 is the width in millimetres, 80 the ratio of height to width as a percentage, R indicates radial construction and 22.5 the rim diameter in inches. The load indexes follow, often dual (for example 156/150: single and twin fitting), and the speed code. Markings such as 3PMSF or M+S may also appear on the sidewall. The size must be chosen from those specified for the vehicle, because capacity and dimensions change.

Sources: professional.michelin.it, goodyear.eu

They are rim diameters in inches, and each diameter requires tyres of its own size. Michelin explains that smaller-diameter tyres lower the overall height of the vehicle and allow semi-trailers with more internal volume, but it does not recommend them for long distances; larger diameters give more ground clearance, useful for example in the mountains or on rough surfaces. The diameter is not freely chosen: follow the sizes specified for the vehicle and state them in the quote request.

Sources: professional.michelin.it

It is a tyre 385 mm wide, with a sidewall equal to 65% of the width, for a 22.5 inch rim. It is a size used in single fitting mainly on trailer axles: Michelin offers it, for example, in the range for the trailer position. It should not be confused with "super single" tyres with a lower profile, such as the 495/45 R22.5, which can replace twin fitting on the drive axle. The choice must respect rims, approval and the sizes specified for the vehicle.

Sources: professional.michelin.it, professional.michelin.it

The first number (156) is the load index for single fitting, the second (150) for twin fitting. The letter L is the speed code and corresponds to 120 km/h. The indexes are codes, not kilograms: they refer to a table of maximum loads per tyre. The tyre must have load and speed indexes suited to those specified for the vehicle.

Sources: goodyear.eu, michelin.it, professional.michelin.it

They are designed for different tasks. Michelin identifies them with letters: F for the steer axle (load, dynamic transfers, precision), D for the drive axle (traction), T for the trailer (static and dynamic loads, scrubbing, mileage) and Z for multiple positions. On the trailer axle only T or Z treads are used. Fitting a tyre in the wrong position can worsen wear and safety. That is why in the quote we need to know the axle it is fitted to.

Sources: professional.michelin.it

Retreading replaces the worn tread of a tyre with a new one, reusing the casing. It is common for lorries, trailers and buses: it reduces costs and consumption of raw materials, and retreaded tyres must undergo checks. Quality depends on the casing, which must be sturdy. Michelin designs Remix retreads for drive and trailer axles and advises against fitting them on the first steer axle.

Sources: professional.michelin.it, professional.michelin.it

C3 is the class of tyres for heavy vehicles (lorries and buses) in the European label; C1 covers cars, C2 light commercial vehicles. The label shows rolling resistance class (A to E), wet grip (A to E) and external noise in dB with class from A to C, plus the 3PMSF snow symbol if the tyre has it. The ice symbol can currently appear only on C1 tyres, not on C2 or C3. The reference is Regulation (EU) 2020/740.

Sources: energy-efficient-products.ec.europa.eu, energy-efficient-products.ec.europa.eu

Yes: lorry tyres can also have the 3PMSF marking, which indicates passing regulatory snow grip tests, and manufacturers offer winter ranges for lorries. The M+S marking alone, however, does not require performance tests: it is at the manufacturer's discretion. For heavy vehicles too the snow symbol can appear on the European label. For the choice take into account the axle of fitment (steer, drive, trailer) and the type of service.

Sources: professional.michelin.it, michelin.it, energy-efficient-products.ec.europa.eu

It depends on load, speed and conditions of use: according to Michelin, once these elements are determined there is only one suitable pressure, and manufacturers publish inflation tables. In any case the pressures recommended by the vehicle or tyre manufacturer must be respected. Insufficient inflation raises the tyre's temperature and degrades its components; over-inflation also carries risks. Check the pressure regularly with cold tyres.

Sources: professional.michelin.it

The most common causes are incorrect pressure, misadjusted wheel alignment (toe, camber), worn suspension components and badly distributed loads. Uneven wear, for example heavier on one edge or in ridges, is a sign to have checked. Correcting the cause before fitting new tyres avoids the problem happening again. Periodic checks of pressure and alignment help get more out of the tyres.

Sources: professional.michelin.it, michelin.it

It depends on use. Michelin, for example, divides its lorry ranges into long haul (high constant average speed, international trips), national and regional transport on all types of road and use on roads in and near construction sites and quarries, where sturdier tyres are needed. The same size can exist in different versions. Choose based on the vehicle's real service, not on the size alone.

Sources: professional.michelin.it

You need the complete size (for example 315/80 R22.5), the load indexes and the speed code, and the axle of fitment: steer, drive or trailer, because different tyres are used for each position. Pneumatici SuperStore prepares quotes for lorries and HGVs in which you choose the axle. If you don't know the size, you find it on the sidewall of the fitted tyre or in the vehicle's documents.

Sources: professional.michelin.it