LT vs P-Metric Tires: What's the Difference?

LT-metric tires are built for light trucks and provide the full load capacity branded on the sidewall. Euro-metric and P-metric tires were designed for cars. On vans, pickups, crossovers and SUVs, their sidewall load is divided by 1.1 (source: Tire Rack).

Tire Rack says the differences in load capacity and inflation pressure often make swapping a set of one type for the other inappropriate. Check your driver door placard, owner's manual, or a tire technician before you choose a type.

Why is a P-metric tire's load figure divided by 1.1 on a truck?

Tire Rack says Euro-metric and P-metric sizes were designed for cars. On a passenger car, the tire is used at its sidewall load rating.

Tire Rack gives the reason for the change on trucks: vans, pickups, crossovers and SUVs have a higher center of gravity and a greater probability of being overloaded than passenger cars. For these vehicles, Tire Rack says vehicle engineers are required to specify Euro- or P-metric tires rated to carry 10 percent more weight.

Tire Rack describes this as the equivalent of dividing the load capacity branded on the sidewall by 1.1. The result is a load limit 9.1 percent below the sidewall figure (calculated from the formula). Tire Rack says LT-metric tires are built for light trucks and provide their full sidewall load capacity.

How do you calculate the truck load limit for a P-metric tire?

1. Find the maximum sidewall load rating. In the Tire Rack example, a tire is rated for 2,000 pounds on a passenger car (907 kilograms, calculated conversion).
2. Apply the divisor. Tire Rack says the sidewall load is divided by 1.1 when the tire is used on a van, pickup truck, crossover or SUV.
3. Calculate the adjusted load limit. 2,000 pounds divided by 1.1 is 1,818 pounds (825 kilograms, calculated conversion). Tire Rack gives the same 1,818 pounds in its example.
4. Find the difference. 1,818 pounds is 9.1 percent below 2,000 pounds (calculated from the formula).

The sources do not say what load your vehicle needs. Take the vehicle's tire requirements from its door placard and owner's manual, or ask a tire technician. To compare overall tire dimensions, use the tire size calculator. To read the markings on a tire, see how to read a tire sidewall.

What are the main differences between LT and P-metric tires?

The comparison below uses only statements from Tire Rack.

Tire Rack says LT-metric tires are built strong. For another truck-size comparison, see the 265/70R17 vs 285/70R17 guide.

What do the sources say about inflation pressure and replacement?

• Use the vehicle manufacturer's pressure. NHTSA says the correct pressure is the one the vehicle manufacturer lists on the Tire and Loading Information label on the driver's door edge or in the owner's manual, not the figure printed on the tire.
• LT tires use higher pressure. Tire Rack says LT-metric tires use higher inflation pressures to carry a given load and provide the desired safety margin.
• Measure pressure cold. NHTSA says cold means the car has not been driven for at least three hours. NHTSA also recommends checking the pressure of all tires, including the spare, at least once a month.
• Do not mix the types. Tire Rack says the differences in load capacity and required inflation pressure prohibit mixing LT-metric tires with Euro- or P-metric tires.
• Swapping a whole set. Tire Rack says these differences often make it inappropriate to swap a set of one type for dimensionally equivalent tires of the other. Ask the vehicle manufacturer's documentation or a tire technician first.

For a checklist before installing replacement tires, see what to check on used tires.

Frequently asked questions

Can I replace P-metric tires with LT tires on an SUV or truck?

Tire Rack says differences in load capacity and inflation pressure often make swapping a set of one type for the other inappropriate. Check your vehicle placard or owner's manual, or ask a tire technician, before switching.

Why is the load of a P-metric tire divided by 1.1 on a truck?

Tire Rack gives two reasons: vans, pickups, crossovers and SUVs have a higher center of gravity and a greater probability of being overloaded than passenger cars. Its example: a 2,000 lb tire is limited to 1,818 lb on such a vehicle.

Can I mix LT and P-metric tires on the same vehicle?

Tire Rack says the differences in load capacity and required inflation pressure prohibit mixing LT-metric tires with Euro- or P-metric tires. For your vehicle, ask a tire technician.

Sources

• Tire Rack: Do Euro/P-Metric Tires Carry Less Load When Installed on a Truck?
• Tire Rack: Light Truck (LT) Tires vs. Passenger Tires
• NHTSA: Tire Safety and Maintenance