P-Metric vs LT Size Comparator
Compare a car tire with a light truck tire. Use the calculator below. Results update as you type.
How the P-Metric vs LT Size Comparator Works
This comparator works by comparing the load capacity of P-metric and LT-metric tires with the same dimensions. It applies the 1.10 derating rule for P-metric tires on trucks.
- Enter the size, for example 265/70R17.
- Read the P-metric load: index 113 (1,150 kg).
- Read the derated P-metric load on a truck: 1,045 kg.
- Read the LT load: index 121 (1,450 kg), load range E.
The Formula
The formula is Derated Load = P-Metric Load ÷ 1.10.
Derated Load = Load_P ÷ 1.10 LT Load = LI_Table[LT Single Index] Gain (%) = (Load_LT − Derated Load) ÷ Derated Load × 100The 1.10 factor applies when a P-metric tire is fitted to a light truck, van or SUV used for heavy hauling. Worked example: P275/70R18 at 1,250 kg derates to 1,136 kg; LT275/70R18 at index 125 carries 1,650 kg, a 45% gain.
Conversion Table
The conversion table compares 7 sizes in P-metric and LT form. Each row lists the P-metric index, its derated load, the LT single index and the load range.
The load range C size (235/75R15) carries less than the derated P-metric version. Load range E sizes carry 28–50% more than the derated P-metric load.
| Size | P-Metric Index | P-Metric on Truck (÷1.10) | LT Single Index | LT Load Range |
|---|---|---|---|---|
| 265/70R17 | 113 (1,150 kg) | 1,045 kg | 121 (1,450 kg) | E |
| 275/65R18 | 114 (1,180 kg) | 1,073 kg | 123 (1,550 kg) | E |
| 245/75R16 | 109 (1,030 kg) | 936 kg | 120 (1,400 kg) | E |
| 265/75R16 | 114 (1,180 kg) | 1,073 kg | 123 (1,550 kg) | E |
| 235/75R15 | 108 (1,000 kg) | 909 kg | 104 (900 kg) | C |
| 275/70R18 | 116 (1,250 kg) | 1,136 kg | 125 (1,650 kg) | E |
| 285/70R17 | 116 (1,250 kg) | 1,136 kg | 121 (1,450 kg) | E |
Fitment data varies by brand; read the exact service description on the tire you buy.
What Is the P-Metric vs LT Size Comparator?
The P-Metric vs LT Size Comparator is a tool that compares passenger (P-metric) and light truck (LT-metric) versions of the same tire size. The dimensions match, but the construction and load standards differ.
P-metric tires ride softer and weigh less. LT tires carry more at higher pressure and resist punctures better. The comparator shows the load trade-off in numbers.
Common Uses
This comparator has 4 uses: towing decisions, ride decisions, derating checks and pickup upgrades.
- Decide for towing: See the capacity gain of LT tires.
- Decide for ride quality: Weigh a softer P-metric ride.
- Apply derating: Know the real P-metric capacity on a truck.
- Upgrade pickups: Move from P-metric to LT for work use.