Choosing the right truck tires directly impacts safety, legality, and total lifecycle costs of your fleet. Understanding the technical markings on your truck tires—specifically the load index—is fundamental to running an efficient business. This expert guide breaks down how to identify, calculate, and implement the correct truck tire load index.
Choosing the right truck tires directly impacts safety, legality, and total lifecycle costs of your fleet. Understanding the technical markings on your truck tires—specifically the load index—is fundamental to running an efficient business. This expert guide breaks down how to identify, calculate, and implement the correct truck tire load index.
- Truck tires must meet or exceed the load capacity specifications outlined in the registration documents to pass inspections and avoid roadside fines.
- Load index requirements differ across vehicle axles. Identical tread patterns and load indexes are required on the same axle.
- The heavy battery of electric trucks demands robust truck tires with significantly higher load indexes.
- Nokian Tyres offers a wide range of truck tires for both on- and off-road use. Use our heavy tire selector to find truck tires with the right load index.
Load index of truck tires
The load index is an international numerical code that specifies the maximum weight in kilograms a single truck tire can safely support. It is located on the sidewall of your truck tires, immediately after the tire size.
The truck tire load index can also be found in the manufacturer's manual. Look up your specific tire size to find clear tables of the axle load capacities for different truck tire pressures. The load index is paired with a speed symbol, together designated as the LI/SS (Load Index / Speed Symbol) in the manual.
Single vs. dual load index configurations on trucks
It is crucial to understand how truck tire configurations impact load-bearing capacity:
- Single configuration (one wheel per side): This refers to two wheels total on the truck tire axle. Steering axles are always configured with single tires.
- Dual configuration (two wheels per side): This creates a total of four wheels on the truck tire axle, a standard for drive and heavy trailing axles.
“When examining a commercial truck tire, you will typically find two load index numbers displayed in the tables of the manufacturer's manual. For instance, a marking like "156/150K" indicates the tire's load capacity in both single and dual wheel configurations.” - Teppo Siltanen, Senior Product Manager, Nokian Heavy Tyres.
Nokian Tyres Technical Manual provides specific single and dual load indexes because truck tires grouped closely in pairs experience higher heat concentration and slight load imbalances due to road crowning. Consequently, the rated capacity per individual truck tire is lower in a dual setup than in a single setup.
DOWNLOAD THE NOKIAN TYRES TECHNICAL MANUAL
Why should you choose truck tires with the right load index?
Keeping your commercial truck fleet within its weight limits isn't just an operational recommendation—it's how you protect your business from major risks and high costs. Nokian Tyres Senior Product Manager Teppo Siltanen lists five reasons to choose truck tires with the right load index:
1. Fleet safety
Overloading truck tires causes the casing to flex excessively, generating internal heat that can lead to sudden tire failure.
“Commercial drivers should never exceed the truck tires' rated load capacity. Overloading causes heat buildup, which can lead to dangerous blowouts.” - Teppo Siltanen, Senior Product Manager, Nokian Heavy Tyres.
2. Operational efficiency
Your fleet must be equipped to handle the maximum vehicle weight during heavy commercial use. Choosing the correct load index ensures your trucks operate reliably without unexpected mechanical disruptions during transport.
3. Cost management
Choosing truck tires with the right load index can save money in the long run. When you match the right load-bearing capacity with the manufacturer’s recommended tire pressure, your truck tires can last longer in use.
“A truck tire's load capacity and inflation pressure go hand in hand. Maintaining adequate tire pressure is essential to ensuring the tire can safely handle its rated load.” - Teppo Siltanen, Senior Product Manager, Nokian Heavy Tyres.
4. Regulatory compliance
Transportation authorities monitor truck tires during commercial vehicle inspections and roadside police checkpoints. If an inspector identifies a heavy tire that fails to meet the load index specified in the vehicle's official registration documents, the operator faces fines, or the vehicle may be grounded on the spot.
5. Vehicle stability, steering, and braking
The load index of the truck tire directly affects the load capacity and handling dynamics of the vehicle. Using truck tires with the wrong load index or incorrect pressure compromises steering, lengthens braking distances, and reduces grip—putting both the driver and cargo at risk.
Electric trucks require a higher load index
Transitioning to electric trucks means vehicles have a massive increase in empty weight, thanks to heavy battery packs. This extra weight puts more pressure on commercial truck tires that handle heavy loads.
“To handle the constant load of heavy batteries, fleet operators moving to electrical trucks need to choose specialized tires with a higher load index.” - Teppo Siltanen, Senior Product Manager, Nokian Heavy Tyres.
Nokian Heavy Tyres offer durable truck tires engineered for both traditional engines and electric vehicles. Find truck tires with the perfect load index for your fleet.
Frequently asked questions about truck tire load index
What is truck tire load index?
The truck tire load index is a standardized numerical code that tells the maximum weight an individual truck tire can safely support at its rated inflation pressure.
How to determine truck tire load index?
The load capacity is stamped directly onto the sidewall of the truck tire. It is critical to inspect the sidewall and verify these metrics against the manufacturer’s technical manual, especially for retreaded truck tires.
Where can I find the load capacity of my truck tires?
The load capacity of your truck tires is located on the tire sidewall, immediately after the sequence detailing the tire's width, aspect ratio, and rim diameter.
Why do commercial tires have two load ratings?
Commercial truck tires have two load ratings to display for both single and dual wheel configurations. The first number applies to single-tire axles, while the second applies to two tires paired side-by-side.
How much weight can a truck tire hold?
A truck tire's weight limit is determined by its load index, which specifies the exact number of kilograms it can support. To find these weight equivalents, check the load index tables in the manufacturer’s manual or on their website.
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Please remember that it is the driver’s responsibility to ensure their tires are safe and suitable for their vehicle and to follow the vehicle’s manufacturer´s guidelines for proper use and maintenance. Consult your closest Nokian Tyres dealer or your vehicle’s manufacturer for specific advice.
