Standard Load vs XL Comparator
Compare standard load (SL) and extra load (XL) versions of the same tire size. Capacity, reference pressure and when XL is needed.
Compare published load and pressure specifications.
Standard Load vs XL Comparator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How Standard Load vs XL Comparator Works?
The Standard Load vs XL Comparator works by decoding the load index of the SL and XL versions of one size and comparing capacity at each version's reference pressure. The tool uses 3 steps.
Enter the size
Type the size, for example 235/45 R18.
Enter both indexes
Type the SL index (94) and the XL index (98).
Compare
The comparator returns 670 kg vs 750 kg (1,477 lb vs 1,653 lb), +80 kg (+11.9%), with reference pressures of 2.5 bar (36 psi) for SL and 2.9 bar (42 psi) for XL.
Standard Load vs XL Comparator Formula
The Standard Load vs XL Comparator formula is ΔL = L(i_XL) − L(i_SL), measured at the reference pressure of each construction.
ΔL = L(i_XL) − L(i_SL)i_XL ≈ i_SL + 3 to 4P_SL = 2.5 bar ; P_XL = 2.9 bar- i_SL, i_XL
- Standard and extra load index
- P_SL, P_XL
- Reference pressures (bar)
Worked example
A 255/35 R19 tire carries 630 kg (1,389 lb) as 92 SL and 710 kg (1,565 lb) as 96 XL, a gain of 80 kg (176 lb), +12.7%.
Standard Load vs XL Comparator Conversion Table
The Standard Load vs XL Comparator conversion table compares SL and XL capacity for 6 passenger sizes.
| Size | Standard load | Extra load | Gain |
|---|---|---|---|
| 205/55 R16 | 91 = 615 kg (1,356 lb) | 94 XL = 670 kg (1,477 lb) | +55 kg (+8.9%) |
| 225/45 R17 | 91 = 615 kg (1,356 lb) | 94 XL = 670 kg (1,477 lb) | +55 kg (+8.9%) |
| 235/45 R18 | 94 = 670 kg (1,477 lb) | 98 XL = 750 kg (1,653 lb) | +80 kg (+11.9%) |
| 245/40 R18 | 93 = 650 kg (1,433 lb) | 97 XL = 730 kg (1,609 lb) | +80 kg (+12.3%) |
| 255/35 R19 | 92 = 630 kg (1,389 lb) | 96 XL = 710 kg (1,565 lb) | +80 kg (+12.7%) |
| 275/40 R20 | 102 = 850 kg (1,874 lb) | 106 XL = 950 kg (2,094 lb) | +100 kg (+11.8%) |
What is Standard Load vs XL Comparator?
A Standard Load vs XL Comparator is a tool that compares the 2 passenger tire constructions sold in many sizes: standard load (SL) and extra load (XL). XL tires use a stronger carcass that holds more pressure and carries more weight.
XL capacity only appears at XL pressure. An XL tire run at SL pressure carries about the same load as an SL tire.
Plus-size fitments, heavy EVs and SUVs often need XL to match the original load index.
What are the uses of Standard Load vs XL Comparator?
There are 4 main uses of the Standard Load vs XL Comparator, including plus-size load matching and EV tire choice.
Plus-size load matching
Use XL to restore load capacity on a lower-profile tire.
EV tire choice
Carry battery weight with XL capacity.
Pressure setting
Set XL pressure to reach the placard load.
Cost comparison
Decide whether the XL price premium is needed.
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