The wheels for light trucks and minibuses are usually require a specialized Commercial tyres. In fact, these are car tyres of a reinforced design that are able to withstand increased loads. In the name of such tyres, after indicating the rim diameter, there is a letter C. A good example of this is Lassa Transway 225/70 R15C 112T.

Heavy trucks and buses have very different requirements for tyres, not to mention specialized vehicles. Different types of tyres are installed on different axles of heavy trucks.

Classification by type and mounting places

Truck tyres are classified according to type with reference to the mounting place, i.e. for specific vehicle axles:

  • steer tyres are designed for mounting on a steer axle; their design takes into account the increased torsional loads in the vertical plane impacting the shoulder area of the tyre;
  • drive tyres are placed on the drive axles of the car; they take on the force of friction, have increased torsional strength along the main axle of rotation, and in the top models various design tricks are used to improve grip properties to avoid skidding;
  • trailer tyres are mounting on free-rolling axles, which are most often found on trailers – hence the name; such tyres have the greatest resistance to loads by weight and have minimal rolling resistance;
  • universal tyres are mounted in all positions, however, they are inferior in terms of driving performance to models for specific axles; A significant plus of universal truck tyres is that the driver does not need to carry a large number of spare tyres.
Popular drive axle truck tyres

The type of truck tyre can be identified by the following markings:

1. S (Steer) – steer axle.

2. D (Drive) – drive axle.

3. T (Trailer) – trailer axle.

4. U (Universal, All Position) – universal tyre (usually, the letter U is not indicated in the marking).

In practice, such markings look like this: Continental Conti Hybrid H S 3 Plus, Barum B D 200 Road, Michelin X T E3, etc. Note that there are no common principles for marking tyres by the installation axles. For example Michelin marks steer tyres with the letter F (Front), and universal tyres with the letter Z, which is out of the general rules. These points need to be clarified in advance.

Suitable tyres must be unstalled to each truck axle.
Good to know. Many models of steer truck tyres can be used first on a steer axle, and after a certain mileage, they can be rearranged on trailer axles if the speed rating and load index match. Also, steer and universal tyres with longitudinal tread pattern are most often installed on the bus wheels – it is this tyres that provide a quiet and comfortable ride.

In the markings of tyres for agricultural and special equipment, the following designations can be found:

  • L2 – for sand and soft soil.
  • L3 – usual tread depth for asphalt and concrete pavements.
  • L4 – for stony rocks.
  • L5 – for rocks.
  • E (Earthmover) – for dump trucks, towing vehicles, earth-moving machines (scrapers).
  • L (Loader) – for loaders.
  • G (Grader) – for graders.
  • MCS (Mobile Crane Service) – for truck cranes.
  • OTR (Off The Road) – for self-propelled units and other special equipment.
  • POR (Professional Off-Road) – professional off-road tyres for construction equipment, mining trucks, etc.

The vast majority of truck tyres are radial. The cord in their frame is located along the meridian at an angle of about 0°, in the belt – at an angle of at least 65°, crossing in adjacent layers. It sounds complicated, but it is radial tyres that are characterized by a long service life, improved traction and low rolling resistance. In the design of diagonal tyres, the carcass and belt cord in adjacent layers intersect; in the middle part the slope angles range from 45° to 60°.

Radial tyres marking

Metric system

Marking the size of truck tyres in the metric system is almost the same as the principles for designating car tyres, which is described in detail in the article Tyre Marking from A to Z.

Take, for example, a tyre 315/80 R22.5 156/150L :

  • 315 – tread width in millimetres;
  • 80 – percentage ratio of the sidewall height to the tread width; in this example, 80% of 315 mm is equal to 252 mm;
  • R – radial type of tyre construction; less often there are designations of other structures - D (diagonal) and B(bias);
  • 22.5 – rim diameter in inches;
  • 156/150 – load indices; the first number is the load with single tyres, the second number is when tyres are installed in a pair (for twin wheels);
  • L – speed rating (up to 120 km/h).
The main parameters in specifying the size of truck tyres.

In the American manner, the marking of truck tyres looks a little different. Before specifying the size, letters have been added that indicate the area of use of tyres. It looks something like this:


LT 185/75 R16.

  • P (Passenger) – passenger car tyres;
  • LT (Light Truck) – light truck tyres;
  • T (Truck) – truck tyres.

Inch system

Truck tyre markings in the inch system are presented in a completely different way. Let's look at an example:


12.00 R20

  • 12 – section width in inches;
  • .00 – the ratio of the sidewall height to the width, expressed as a percentage; in this case, it is 100% – the number one in the designation is omitted.; a model marked 8.25 will have a width of 8", and a sidewall height – 125% of the width;
  • R – radial tyre;
  • 20 – rim diameter in inches.

If the profile (aspect ratio) in a radial tyre is not specified (for example, 13 R22.5), then it is assumed by default to be 80% of the tread width.

Key markings on the sidewall of truck tyres.
  • 1. Additional information place (most often, information about the company that retreaded the tyre is added here: logo, certificate number, retread date.)
  • 2. ECD (Goodyear technology, that provide protecting of the tyre sidewalls with a corrosion-resistant polyamide belt.)
  • 3. DOT (Department of Transportation) – US standard. (Both labels E and DOT applied if the tyre certified for EU and US markets. DOT letters followed by manufacturing code, and date of manufacture.)
  • 4. REGROOVABLE (Label that tyre may be regrooved down)
  • 5. Tyre construction and design information (RADIAL – radial design; UNISTEEL – strong steel-belt package; TUBELESS – requires no inner tube; M+S – Mud+Snow, winter tyre)
  • 6. Country of origin
  • 7. MAX LOAD SINGLE/DUAL (Approved for the US market tyres must have a textual interpretation of the indexes: load range (G/K), test pressure (125PSI), maximum load on a single and a dual wheel.)
  • 8. Tyre size
  • 9. Label indicates tyre EU certification
  • 10. TEST INFL. – maximum tyre pressure
  • 11. Load index/Speed rating (The speed rating is the maximum speed at which a tyre is capable of transporting the load indicated in the load index.)

Key markings on the sidewall of truck tyres.
  • 1. Section width in inches. In the leftmost example, both the tyre width and profile are indicated. Two zeros after a dot meaning the ratio of the sidewall height to the width is 100%. If the aspect ratio is not specified in the radial tyre (13R22.5) then it defaults to 80%.
  • 2. Section width in millimetres.
  • 3. Profile (aspect ratio). The ratio of the sidewall height to the width (%).
  • 4. Design type.The «R» letter means a radial design. For diagonal tyres the «-» symbol is used.
  • 5. The rim diameter in inches.

In general, it should be noted that wide-profile truck tyres are great for off-road driving, low- and ultra-low profile tyres are the best options for stable driving on the highway.

Diagonal tyre marking

In diagonal tyres, the size is written with a hyphen as follows:


14.00-20 or 355-20

  • 14.00 – section width in inches;
  • 355 – section width in millimetres.;
  • 20 – rim diameter in inches.

There is another marking for diagonal tyres: 16/70-20.

  • 16 – tread width in inches;
  • 70 – aspect ratio of the sidewall height to the width (70% of 16 inches);
  • 20 – rim diameter of the truck tyre.

Tyres for loaders, special equipment and agricultural vehicles can be marked as follows: 16*6-8.

  • 16 – outer tyre diameter in inches;
  • 6 – section width in inches.;
  • 8 – rim diameter in inches.

Load index and speed rating, ply rating

In trucks and buses, the load is often unevenly distributed along the axles. It may vary depending on the location of the cargo or passengers. The load index determines the highest weight load at which the tyre retains its driving properties without loss of strength and the risk of accidents. The parameter is calculated at the maximum allowable tyre pressure and maximum speed.

In the marking of truck tyres, the load index is often written as a fraction: 152/148, 154/150, etc. The first number determines the load on single wheels, the second – the maximum load for paired tyres. Usually, the second number is less – when installing wheels in a pair, a non-uniform load occurs on each tyre when it hits bumps, pits, stones, etc.

Also on the sidewall of the truck tyre there is a double designation of the load index: 152/148 M and next to it 154/150 L Such markings give information on the permissible load on the tyre when operating at different speeds. The car can be loaded more, but you will have to drive more slowly.

Deciphering the load indices for truck tyres are given in the table:

LOAD INDICES
Value Max. load, kg Value Max. load, kg Value Max load, kg Value Max. load, kg
116 1250 137 2300 158 4250 179 7750
117 1285 138 2360 159 4375 180 8000
118 1320 139 2430 160 4500 181 8250
119 1360 140 2500 161 4625 182 8500
120 1400 141 2575 162 4750 183 8750
121 1450 142 2650 163 4875 184 9000
122 1500 143 2725 164 5000 185 9250
123 1550 144 2800 165 5150 186 9500
124 1600 145 2900 166 5300 187 9750
125 1650 146 3000 167 5450 188 10000
126 1700 147 3075 168 5600 189 10300
127 1750 148 3150 169 5800 190 10600
128 1800 149 3250 170 6000 191 10900
129 1850 150 3350 171 6150 192 11200
130 1900 151 3450 172 6300 193 11500
131 1950 152 3550 173 6500 194 11800
132 2000 153 3650 174 6700 195 12150
133 2060 154 3750 175 6900 196 12500
134 2120 155 3875 176 7100 197 12850
135 2180 156 4000 177 7300 198 13200
136 2240 157 4125 178 7500 199 13600

Speed ratings for truck tyres are indicated in letters that contain the maximum allowed speed in km/h. The further the letter in the alphabet, the greater the speed the tyre can develop.

SPEED RATINGS
Value Max. speed, km/h Value Max. speed, km/h
A1 5 E 70
A2 10 F 80
A3 15 G 90
A4 20 J 100
A5 25 K 110
A6 thirty L 120
A7 35 M 130
A8 40 N 140
B 50 P 150
C 60 Q 160

The load capacity of a tyre is described not only by load index, but also by ply rating (PR). This indicator reflects the number of plies of the tyre cord. It is written as 18PR, 20PR, etc. The larger the number before the abbreviation PR, the greater the air pressure and the greater the load the tyre can withstand. However, the rule "the thicker the stronger" does not work here. Modern technologies make it possible to produce durable and wear-resistant tyres with a minimum number of layers, which have excellent performance characteristics. The ply rating should be within the acceptable limits for a particular freight transport.

An increased number of cord plies is also indicated by the designations EL/XL (Extra Load) and Reinforced. Tyres with such marks have a reinforced structure and withstand increased loads.

Tubeless and tube tyres

Tyres for trucks are tubeless ( TL – TubeLess) and tube (TT – Tube Type). Most models has a tubeless design – a sealing cavity is formed by a tyre and a wheel rim due to a rubber layer with increased gas tightness.

Tubeless tyres are labeled TubeLess (TL), tube tyres – Tube Type (TT).

Tube tyres are intended to be used with an appropriately sized air tube. Such tyres are noticeably heavier than tubeless counterparts and are more vulnerable to punctures – in the event of a tube tyre puncture, you will have to disassemble the wheel and glue the tube, while on tubeless tyres there is a higher chance of getting to the truck tyre shop without having to stop for repairs in the middle of the road.

By seasonality and types of road surface

The vast majority of truck tyres are produced in all-weather versions. Winter and summer models of such tyres are very rare. All-season tyres for trucks are marked with a number of special designations:

  • AS (All Season, Any Season) – all-season tyres.
  • AW (All Weather) – all-weather tyres.
  • M&S (Mud & Snow) – tyres for mud and snow.
  • 3PMSF (Three Peak Mountain Snow Flake) – tyres prepared for difficult winter road conditions. Their characteristics meet the requirements of traction and braking on snow or icy roads. The 3PMSF icon is made in the form of an three-peak alpine mountain and a snowflake symbol inside;
  • Aqua, Rain, Water, Umbrella or Rain icons – increased tyre resistance to hydroplaning and improved water drainage.
According to seasonality, truck tyres are most often marked with the designations M+S and the symbol of a three-peaked alpine mountain with a snowflake icon.

According to the types of roadway, truck tyres are divided into the following subcategories:

  • OTR (Off The Road) – tyres for off-road wheeled vehicles;
  • NHS (Non Highway Service) – off-road tyres;
  • MPT (Multi-Purpose Tyres) – tyres for mixed operating conditions.
All season truck tyres

Additional designations

When installing tyres with an asymmetric and directional tread pattern, the following markings must be observed:

1. Outside – outer side of the tyre.

2. Inside – inner side of the tyre.

3. Right, Left – installation on the right and left side of the vehicle, respectively.

4. Rotation with an arrow – the tyre rotation vector in the direction of the truck.

There are other designations on the sidewall of truck tyres:

★★ (Star Rating) – determines the maximum allowable tyre pressure. Also, the test pressure that the model was tested with (for example, 125PSI) may be indicaten on the tyre.

Max Pressure – maximum allowable tyre pressure, expressed in kilopascals or pounds per square inch.

Max Load – maximum load in kilograms or pounds.

REGROOVABLE – technology that allows to cut the tread pattern as the factory layer wears out.

TWI (Tread Wear Indicator) – indication of the remaining height of the tyre tread. It can be used to visually assess the degree of tyre wear.

Treadwear and three digits – tyre wear resistance index.

Traction and the letter from A to E – an indicator of the "wet" grip of the tyre.

Temperature – temperature resistance characteristic.

The date of manufacture of the model is applied in four digits (often in an oval). The first two digits are the serial number of the week, the last two are the year of manufacture. So, behind the marking "2722" is the 27th week of 2022. The country of manufacture of the tyre is indicated by inscriptions in the manner of "Made in Germany".

In tyres marked REGROOVABLE, it is allowed to cut the tread pattern as the factory layer wears out.

All sorts of design tricks that have found implementation in a particular model are marked with the following markings:

  • AllSteel, UNISTEEL – strong steel-belt package.
  • Nylon – tyre with a nylon cord.
  • Solid – solid tyre.

Tyre companies can put their own technological marks on the sidewall of the model. So, on some tyres of the Goodyear brand there is an EDC inscription – this technology involves protecting the sidewalls of the tyre with a polyamide cord. And in the place for additional information, an empty space is often reserved for data on tyre retreading: company logo, certificate number, retread date, etc.

Compliance of the model with quality standards is indicated by the following markings:

  • DOT – American safety standard.
  • E in a circle or ECE – European safety standard.

Rim tape

Sometimes truck tyres are mounted on wheels using a substrate – rim tape. This is an elastic rubber ring that is placed between the tyre beads, the wheel rim. It is used to protect the tube from damage. The dimensions of the rim tape are indicated in millimetres or inches. These markings look like this:

475-633 or 6.7-20

  • 475 – tape width in millimetres, 6.7 – width in inches.
  • 633 – rim diameter in millimetres, 20 – rim diameter in inches.

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Knowing the principles of deciphering the markings, choosing the right truck tyres will not be difficult. The main thing is to approach the choice of tyres correctly and take into account all the above nuances. Properly selected tyres will last a long time and save you from trouble on a long journey.