Snow Performance Comparator
Compare published winter test results and snow traction indexes. Check 3PMSF qualification and convert indexes into braking distance.
Compare published winter test results.
Snow Performance Comparator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How Snow Performance Comparator Works?
The Snow Performance Comparator works by comparing each tire's snow index against the Standard Reference Test Tire (SRTT) and against each other. The tool uses 4 steps.
Match the test
Confirm both results come from the same method, for example ASTM F1805 traction or a magazine snow braking test.
Enter both results
Type the snow indexes, for example 1.10 and 1.20, or the snow braking distances.
Check 3PMSF
The comparator confirms an index of 1.07 or higher meets the Three-Peak Mountain Snowflake (3PMSF) threshold for passenger tires.
Compare
The comparator returns the percent gap and the equivalent braking distance for a 30 m reference stop.
Snow Performance Comparator Formula
The Snow Performance Comparator formula is Snow index = Performance_candidate ÷ Performance_SRTT, and 3PMSF needs index ≥ 1.07 for C1 tires.
SI = P_cand ÷ P_SRTTSI ≥ 1.07 (C1 passenger tires)d_cand ≈ d_SRTT ÷ SI- SI
- Snow traction index
- SRTT
- Standard Reference Test Tire
- d_SRTT
- Reference tire stopping distance
Worked example
A tire with SI 1.20 qualifies for 3PMSF and is 20% better than the SRTT. The candidate stops in about 25.0 m (82 ft) in a test where the SRTT stops in 30 m (98 ft).
Snow Performance Comparator Conversion Table
The Snow Performance Comparator conversion table converts 6 snow indexes into 3PMSF status and an estimated braking distance.
| Snow index | vs reference | Meets 3PMSF? | Estimated stop (SRTT = 30 m) |
|---|---|---|---|
| 1.00 | +0% vs SRTT | No | 30.0 m |
| 1.07 | +7% vs SRTT | Yes | 28.0 m |
| 1.10 | +10% vs SRTT | Yes | 27.3 m |
| 1.15 | +15% vs SRTT | Yes | 26.1 m |
| 1.20 | +20% vs SRTT | Yes | 25.0 m |
| 1.30 | +30% vs SRTT | Yes | 23.1 m |
What is Snow Performance Comparator?
A Snow Performance Comparator is a tool that compares published winter test results under matched conditions. The 3PMSF symbol shows a tire passed a standardized snow traction test. The symbol does not rank tires that pass.
M+S (mud and snow) is a tread design marking with no performance test. A tire marked M+S without 3PMSF has not proved snow traction.
Ice performance has its own test and marking under UNECE Regulation 117. A tire can carry 3PMSF without an ice grip symbol.
What are the uses of Snow Performance Comparator?
There are 4 main uses of the Snow Performance Comparator, including winter tire shopping and legal compliance.
Winter tire shopping
Rank winter tires by tested snow index.
Legal compliance
Confirm 3PMSF where winter rules require the symbol.
All-season checks
Check whether an all-season tire qualifies for 3PMSF.
Test reading
Turn magazine snow tests into percent gaps.
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