UTQG Traction Grade Comparator
Compare UTQG traction grades AA, A, B and C. See the wet braking coefficients behind each grade on asphalt and concrete.
Compare standardized traction grades.
UTQG Traction Grade Comparator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How UTQG Traction Grade Comparator Works?
The UTQG Traction Grade Comparator works by translating each traction letter into the minimum wet sliding coefficients the tire reached in the NHTSA skid test. The tool uses 3 steps.
Enter 2 grades
Type the traction grade of each tire, for example A and AA.
Decode the thresholds
The comparator returns the asphalt and concrete coefficients for each grade.
Compare
The comparator shows the higher grade and the minimum coefficient gap: 0.07 g on asphalt and 0.06 g on concrete between A and AA.
UTQG Traction Grade Comparator Formula
The UTQG Traction Grade Comparator uses the coefficient thresholds in 49 CFR 575.104: a grade needs both the asphalt and the concrete value to clear its limit.
Grade = highest grade where μ_asphalt > A_lim AND μ_concrete > C_limΔμ = μ_lim(grade₂) − μ_lim(grade₁)d ∝ 1 ÷ μ- μ_asphalt, μ_concrete
- Locked-wheel sliding coefficient on wet asphalt and wet concrete
- A_lim, C_lim
- Grade thresholds
Worked example
An AA tire clears 0.54 g on wet asphalt and 0.41 g on wet concrete. An A tire clears 0.47 g and 0.35 g. At the threshold values, a sliding stop on wet asphalt is about 13% shorter for the AA tire.
UTQG Traction Grade Comparator Conversion Table
The UTQG Traction Grade Comparator conversion table lists the 4 traction grades and the wet sliding coefficients behind each grade.
| Grade | Wet asphalt | Wet concrete | Note |
|---|---|---|---|
| AA | Above 0.54 g | Above 0.41 g | Highest grade |
| A | Above 0.47 g | Above 0.35 g | Most common grade |
| B | Above 0.38 g | Above 0.26 g | Lower wet grip |
| C | 0.38 g or below | 0.26 g or below | Minimum acceptable |
What is UTQG Traction Grade Comparator?
A UTQG Traction Grade Comparator is a tool that compares the traction letters molded on US passenger tires. The traction grade measures straight-line wet braking with a locked wheel at 40 mph (64 km/h).
The test does not measure cornering, hydroplaning, dry grip or antilock braking stops. Two A-rated tires can differ a lot in real wet handling.
More than 75% of graded passenger tires carry an A grade, so the grade separates tires only at the extremes.
What are the uses of UTQG Traction Grade Comparator?
There are 4 main uses of the UTQG Traction Grade Comparator, including minimum grade filtering and label reading.
Minimum grade filtering
Exclude tires below A from a shortlist.
Label reading
Explain AA, A, B and C to a buyer.
Budget tire checks
Check the traction grade of low-cost imports.
Test result context
Pair grades with independent wet braking tests.
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