Truck Tyre Guide
This guide aims to help you understand your truck tyre's size, load carrying capacity, speed rating and axle position.
Metric Truck Tyre Sizes - 295/80R22.5, 315/80R22.5, 385/65R22.5
Modern radial truck tyres are marked up with metric sizes such as 295/80R22.5, 315/80R22.5, 385/65R22.5. The first number in the tyre size marking is the width of the tyre in millimetres looking at it face on. The last number is the truck tyres rim diameter (the hole in the centre of the tyre) in inches. The letter 'R' informs us its of Radial construction (and not the much older Crossply construction). The second number after the '/' is a profile percentage, if you apply this to the tyre width figure it tells you the height of the tyre's sidewall sections, which is useful if you wanted to estimate the truck tyres total height (add two of your sidewall heights to the rim diameter). So a 295/80R22.5 would have sidewall sections that are roughly 295mm x 80% = 236mm tall. Total tyre height should then roughly be 236mm x 2 + 22.5 inches = 1043mm (41 inches). Getting the profile correct is important as it ensures that you maintain your tyres heights so that you don't disrupt axle heights, gearing ratios or transmission performance.
Imperial Truck Tyre Sizes - 10R17.5, 12R22.5, 10.00R20, 12.00R20
Some truck & bus tyres still use the more uncommon imperial truck tyre size markings like 10R17.5, 12R22.5. With these markings the first number is the width of the truck tyre in inches, the 'R' symbolises the construction is Radial, though some classic trucks may have a '-' instead which means it's of Crossply construction. The final number is the tyres rim diameter in inches (size of the hole in the centre of the truck tyre). With these older markings the tyres profile percentage isn't listed, but it is generally assumed that the profile percentage is around 85%. If the size has '.00' included such as 10.00R20, 12.00R20 then these often have a profile closer to 100%.
Truck Tyre Axle Positions - Steer, Drive, Trailer, All Position
Truck tyre requirements vary depending on the axle they are being used on (Steer, Drive, Trailer). The steering axle is the front axle which needs tyres that can handling the turning stresses put on them and be capable of providing a precise steering response. Drive axles are those which provide the power to move the vehicle forward, and these tyres are designed to be able to cope with the stresses that the transmission and braking systems place on them. They often have a tread designed to give more traction instead of focusing on high mileage. Trailer position axles are those which are neither steer or drive axles and are usually just focused on carrying weight. Trailer tyres are designed to provide high mileage, protect against scrubbing, and to cope with the stresses put on them from static and dynamic loads. It is important to select the correct tyre for your axle position to maintain correct operation of your vehicle, comply with UK road legislation, maintain valid insurance and to maximise your investment in your truck tyre purchase by maximising it's service life.
To complicate things somewhat some tyres can serve more than one role depending on the type of vehicle that they are being fitted to (Truck, Bus, Construction Vehicle) and how it is being used (Regional, Long Haul, Urban, On-Off Road). These are often, but not always, labelled as 'All Position Tyres'. This can make truck tyre buying a confusing process. We recommend ensuring you first confirm what tyre load and speed index you need (either by sticking with what you have now, or by checking user manuals or manufacturers websites). After that check which axle you are buying for then examine the options which show for that usage on our site. With each result read the manufacturers description and check their technical documentation on their own websites to ensure they fully fit the vehicle and usage type you require.
Load Rating / Speed Index - 143J, 156M, 160K
Modern radial truck tyres will all have a load and speed index stamped onto the tyre sidewall. They indicate how much weight the tyre can carry when travelling at a certain maximum speed. The marking is usually a series of 3 numbers with a letter after them, such as '156M'. The table below can be used to look up what that first number (load index) means in Kilograms (156 = 4000 kg) and the table below that shows the speed that the letter (speed index) represents (M = 81MPH). So a 156M truck tyre can carry a maximum of 4000kg at a maximum speed of 81 MPH. Many truck tyres have a dual load and speed index marking such as 156/152M, where the lower second 3-digit load index number applies only if your tyre is mounted in a dual wheel configuration on the axle.
Winter Truck Tyre Markings - M&S, 3PMSF
To ensure safe winter weather driving some EU countries require tyres to be stamped with either the M&S (Mud and Snow) or 3PMSF (3 Peaks Mountain Snow Flake) markings. It is often only required on Drive position tyres, but some countries such as Norway do require it on Steer and Trailer tyres also. The M&S marking is simply a manufacturers own declaration that their truck tyre is suitable for use in Mud and Snow. It is a non-regulated standard. The 3PMSF marking however is a regulated and comparable measure that declares a tyre has passed a traction test in winter conditions in accordance with UNECE Regulation 117. The symbol for the 3PMSF certification is a snowflake inside a mountain with 3 peaks as the below image illustrates.
Below is a guide for various EU countries and what their legislation currently requires (provided for informational purposes only, may be subject to changes in local regulations, check before ordering).
|Country||Tread Depth Required||M+S or 3PMFS Required||Snow Chains Authorised|
|Austria||5 mm||Drive axles only||Authorised on drive axle tyres, minimum 2 mm|
|Belgium||1.6 mm||No||Authorised in winter conditions|
|Bosnia & Herzegovina||4 mm||Drive axles only||In the absence of an M+S / 3PMSF symbol on the tyres, chains are obligatory along with a shovel and a bag of sand in the vehicle|
|Croatia||4 mm||Drive axles only||Authorised in the absence of M+S / 3PMSF tires, minimum 4 mm|
|Czech Republic||5 mm||Drive axles only||Authorised in the absence of M+S / 3PMSF tyres, minimum 6 mm. Obligatory when indicated on road signs|
|Finland||1.6 mm||No||Authorised in winter conditions|
|Germany||1.6 mm||Drive axles only||Authorised -Speed limited to 50 km/h|
|Greece||2 mm drive axles / 1.6 mm all others||No||Chains compulsory when indicated on road signs|
|Hungary||1.6 mm if the tire dimension is < 750 mm, 3 mm if it is > 750 mm||No||Chains compulsory when indicated on road signs|
|Italy||1.6 mm||No||Compulsory in the absence of M+S / 3PMSF tires, when indicated on road signs|
|Kosovo||4 mm||Drive axles only||Compulsory in winter conditions|
|Luxembourg||1.6 mm||Drive axles only|
|Macedonia||6 mm drive axles / 4 mm all others||All axles||In the absence of an M+S / 3PMSF symbol on the tyres, chains of minimum 4 mm are obligatory, along with a shovel and bag of sand in the vehicle|
|Montenegro||4 mm||Drive axles only||Chains, shovel and bag of sand when roads are snow-covered|
|Netherlands||1.6 mm||No||NOT authorised|
|Norway||5 mm||All axles, including lift axles||Authorised with a requirement to use 3 to 7 pairs of chains depending on the number of axles|
|Poland||1.6 mm (3 mm for coaches)||No||Chains compulsory when indicated on road signs|
|Portugal||1 mm||No||Chains compulsory when indicated on road signs|
|Romania||1.6 mm||Yes||Authorized on drive axles|
|Russia||4 mm||All axles
|Serbia||4 mm||Drive axles only||Chains compulsory on at least 2 drive wheels along with a shovel|
|Slovakia||3 mm||Drive axles only||Authorised in the absence of M+S / 3PMSF tires or if indicated on road signs|
|Slovenia||4 mm||Drive axles only||Authorised in the absence of M+S / 3PMSF tires, minimum 3 mm|
|Spain||1.6 mm||No||Chains compulsory when indicated on road signs|
|Sweden||5 mm||Drive axles only||Authorised|
|Switzerland||1.6 mm||No||Chains compulsory when indicated on road signs|
|Turkey||4 mm||Drive axles only
|UK||1 mm||No||Not compulsory|
Truck Tyre Tread Patterns - On-Off Road, Traction, Steering
Most manufacturers of truck tyres ensure their tread designs fall into one of the below main categories;
Steering - Often feature a ribbed or grooved tread to ensure they deliver precise turning as well as displacing water when needed.
Traction Drive - Often feature larger square or rectangular blocks on the tread to ensure more grip and bite on the road surface to transfer power as effectively as possible.
On-Off Road - Often have more exaggerated or deeper blocks on the tread to ensure grip in muddy or rocky terrain, often coupled with more substantial shoulder sections to protect against scrubbing and other puncture hazards.
Effects of Incorrect Tyre Pressure on Truck Tyres
Failure to maintain the correct truck tyre pressure directly leads to a decrease in a tyres service life. A tyre underinflated by 17% has been shown in some tyres to result in a 10% decrease in the tyres service life, and a 20% over inflation leads to 22% decrease in service life through uneven and un-optimal wear. Underinflated truck tyres also increase your fuel consumption, studies have shown under inflating a truck tyre by 10-30% can increase your fuel consumption by 0-3% depending on tyre usage.
Caring for your Truck Tyres
Truck tyres are made from a mixture of rubber and metal materials that can deteriorate over time depending on how they are used, stored, and the climate (temperature/humidity) they are operated in. Try to keep tyres away from liquids like oil and maintain the correct tyre pressure. Regularly check your truck tyres to look for any damage or areas of uneven wear. If you find anything then have a truck tyre professional carry out a thorough examination of the tread, tyre sidewalls, bead area and rim if needed to ensure your truck tyres are still fit for purpose. If you spot any issues with a deformed or exposed bead wire, delamination of rubber or areas of creasing internally then do not keep the tyre in service.
Leading Brands in the Truck Tyre Market
Truck tyre brands fall into several categories from premium, mid-range, value and budget. Brands like Michelin, Bridgestone and Goodyear lead the way in the premium sector. Mid-range brands like Hankook, BFGoodrich and Kumho are respected. Value brands often come from Asia and manufacturers like Sailun, Double Coin & Zeta offer cost savings but still provided a level of dependable quality. Budget brands tend to come and go in the truck market and often again originate from Asia.
The difference between the categories (besides price) is often the quality of compounds and raw materials used in manufacture, along with the accuracy of the quality and assurance checking stages which could be visual for budget truck tyres, or include x-ray scanning for more premium products. Generally, as with most things, you get what you pay for, and a premium tyre will outlast a mid-range option and usually reduce your fuel consumption and give better handling and breaking performance for example. Many consumers in todays truck market do however place their trust in the value tyre brands and find they get the level of tyre life and performance that suits their needs for the budget they are working too. The only true way to compare them for yourself is to try them and try to keep a record of each truck tyres lifespan by vehicle mileage.