Standard Load vs XL Comparator
See how much more an XL tire can carry. Use the calculator below. Results update as you type.
How the Standard Load vs XL Comparator Works
This comparator works by decoding the load index of the Standard Load (SL) and Extra Load (XL) versions of the same size and showing the extra capacity. XL tires carry more at a higher reference pressure.
- Enter the size, for example 235/45R18.
- Read the SL index and load: 94 (670 kg).
- Read the XL index and load: 98 (750 kg).
- Read the gain: +80 kg (+176 lb) per tire.
The Formula
The formula is Extra Capacity = LI_Table[XL Index] − LI_Table[SL Index].
Extra (kg) = Load_XL − Load_SL Extra (lb) = Extra (kg) × 2.20462 SL reference: 36 psi (250 kPa); XL reference: 42 psi (290 kPa)Worked example: 275/40R20 at SL 102 carries 850 kg; at XL 106 it carries 950 kg, a gain of 100 kg (220 lb).
The XL capacity applies only at the XL reference pressure. At SL pressure, an XL tire carries about the same as an SL tire.
Conversion Table
The conversion table compares SL and XL capacity for 10 common sizes. XL versions add 55–100 kg (121–220 lb) per tire.
The XL index is usually 3–4 points higher than SL in the same size.
| Size | SL Index | XL Index | Extra (kg) | Extra (lb) |
|---|---|---|---|---|
| 205/55R16 | 91 (615 kg) | 94 (670 kg) | +55 kg | 121 lb |
| 225/45R17 | 91 (615 kg) | 94 (670 kg) | +55 kg | 121 lb |
| 225/40R18 | 88 (560 kg) | 92 (630 kg) | +70 kg | 154 lb |
| 235/45R18 | 94 (670 kg) | 98 (750 kg) | +80 kg | 176 lb |
| 245/40R18 | 93 (650 kg) | 97 (730 kg) | +80 kg | 176 lb |
| 215/55R17 | 94 (670 kg) | 98 (750 kg) | +80 kg | 176 lb |
| 225/50R17 | 94 (670 kg) | 98 (750 kg) | +80 kg | 176 lb |
| 255/35R19 | 92 (630 kg) | 96 (710 kg) | +80 kg | 176 lb |
| 275/40R20 | 102 (850 kg) | 106 (950 kg) | +100 kg | 220 lb |
| 235/55R19 | 101 (825 kg) | 105 (925 kg) | +100 kg | 220 lb |
SL capacity is rated at 36 psi (250 kPa); XL capacity is rated at 42 psi (290 kPa).
What Is the Standard Load vs XL Comparator?
The Standard Load vs XL Comparator is a tool that compares the load capacity of Standard Load and Extra Load versions of a tire size. XL tires, marked "Reinforced" or "RF" on some brands, have a stronger casing built to run at higher pressure.
Heavy electric vehicles and SUVs often need XL tires to meet the placard load index. Swapping XL for SL on those vehicles can leave the tires under-rated.
Common Uses
This comparator has 4 uses: EV tire checks, placard compliance, pressure setting and towing upgrades.
- Check EV tires: Confirm heavy EVs get XL capacity.
- Meet the placard: Match the placard's XL requirement.
- Set pressure: Use XL reference pressure when loaded.
- Upgrade for towing: Add capacity on the rear axle.