EU TYRE GRADE BRAKING TEST
See how tyre factors affect real-world stopping distance
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EU Wet Grip Grade
EU Tyre Label - Wet Grip (A-E)
The Wet Grip rating is a critical safety feature - it indicates braking distance on wet asphalt. The difference between grades can mean 3-6 extra metres per class!
- A: Shortest braking - 15% grip bonus in wet
- B: Great - 6% grip bonus
- C: Baseline performance
- D: Longer braking - 11% grip penalty
- E: Longest braking - 20% grip penalty
Look for this label on tyre sidewalls or in product listings. Wet grip decreases as tread wears!
Source: EU Regulation 2020/740 | EC Energy Label Database
EU Fuel Economy Grade
EU Tyre Label - Fuel Efficiency (A-E)
The Fuel Efficiency rating indicates rolling resistance (RRC) - how much energy the tyre loses as it rolls.
- A: RRC ≤ 6.5 - Best fuel economy
- B: RRC 6.6-7.7 - Very good
- C: RRC 7.8-9.0 - Average
- D: RRC 9.1-10.5 - Below average
- E: RRC ≥ 10.6 - Highest resistance
Effect on braking:
Negligible for normal braking (<0.5% effect). Rolling resistance contributes ~0.05-0.10 m/s² vs braking friction at ~7-10 m/s².
This setting only significantly affects coasting scenarios - when brakes cannot overcome gravity (steep downhill + low friction surfaces).
For braking performance, the EU Wet Grip grade (above) is the relevant measure.
EU Reg. 2020/740 (C1 tyres). Look for the fuel pump icon on the EU tyre label.
Vehicle & Weight
Vehicle Weight & Braking
Heavier vehicles require more distance to stop due to increased momentum. Weight affects tyre load distribution and braking dynamics.
- Hatchback: ~1200kg - Light, responsive braking
- Sedan: ~1500kg - Standard performance
- SUV: ~2000kg - Higher center of gravity
- Ute/Truck: ~2500kg - Heavy, longer stopping
You can enter your exact vehicle weight below, or select a preset.
Find your vehicle's kerb weight on the driver's door jamb sticker or in the owner's manual.
Tyre Size
Understanding Tyre Sizes
Enter your tyre size to automatically set width and max tread depth.
Metric Format (most common):
205/55R16 = Width 205mm / Aspect 55% / Rim 16"
265/60R18 = Width 265mm / Aspect 60% / Rim 18"
Imperial Format (4WD/trucks):
31x10.5R15 = Diameter 31" / Width 10.5" / Rim 15"
33x12.5R17 = Diameter 33" / Width 12.5" / Rim 17"
Max Tread Depth by Tyre Size:
- Small (155-185mm): ~7-8mm new tread
- Standard (195-215mm): ~8-9mm new tread
- Large (225-255mm): ~9-12mm new tread
- 4WD/Truck (265mm+): ~12-16mm new tread
Tread Depth
Tread Depth Matters
Tread grooves channel water away from the tyre. Less tread = less water evacuation = longer stopping distances.
- 8mm (New): Full performance
- 5mm: Still good, monitor regularly
- 3mm: Replace soon - grip drops sharply below 4mm
- 1.6mm: NZ legal minimum - DANGEROUS in wet!
How to Check Your Tread Depth:
- Tread Wear Indicators (TWI): Look for small raised bars in the tread grooves. If tread is level with these, you're at 1.6mm - replace immediately!
- 20c Coin Test: Insert a NZ 20c coin into the groove. If you can see the "20" text, your tread is below 3mm.
- Tread Depth Gauge: Available at auto stores for ~$5. Most accurate method.
- Check Multiple Spots: Measure at least 3 places across the tyre - uneven wear indicates alignment issues.
At 1.6mm, wet stopping distance can be nearly double compared to new tyres. Below 4mm, grip performance drops dramatically!
Weather Conditions
Weather & Water Depth
More water on the road means less rubber-to-road contact and lower grip.
- Dry: Best grip - full tyre contact
- Damp: Slight film (0.1mm) - minor impact
- Light Rain: 0.3mm water depth
- Rain: 0.7mm - significant grip reduction
- Heavy Rain: 1.5mm - Major grip loss!
EU Wet Grip grades matter most when roads are wet!
Dry 1mm
Wet 2.5mm
Pooling 5mm
Flooding
- Light rain (2mm/hr): ~0.2-0.5mm on well-drained roads
- Moderate rain (5mm/hr): ~0.5-1.5mm
- Heavy rain (15mm/hr): ~1.5-3mm
- Torrential (30mm/hr): ~3-5mm+ (hydroplaning likely!)
Tyre Age
Rubber Degrades Over Time
Even unused tyres lose grip as rubber oxidises and hardens. This happens regardless of tread depth!
- 0-3 years: Full performance
- 4-5 years: Monitor condition
- 6-8 years: 15-20% grip loss - consider replacing
- 10+ years: 30%+ grip loss - REPLACE regardless of tread!
Check the DOT code on your sidewall to find manufacture date.
Tyre Type
Tyre Compound Types
Different tyres use rubber compounds optimised for specific temperature ranges.
- Summer: Best above 7°C. Hardens in cold, losing grip. Most common in NZ - fitted to nearly all new vehicles.
- All-Season: Compromise for year-round use. Moderate performance in all conditions. Growing in popularity in NZ, especially South Island.
- Winter (3PMSF): Softer compound stays flexible below 7°C. +8-15% wet/snow grip in cold. Look for Alpine symbol (mountain with snowflake). Essential for NZ ski trips or South Island winter driving.
What's on NZ Roads?
~85% Summer tyres - Most passenger vehicles
~12% All-Season - SUVs, South Island vehicles
~3% Winter - Alpine areas, ski enthusiasts
If you drive to the snow or through Central Otago in winter, consider All-Season or Winter tyres!
Terrain Category
Tyre Terrain Categories
Different tyres are designed for different surfaces. Using the wrong type significantly affects grip and stopping distance.
- Passenger Car (PC): Standard road tyres - baseline performance
- Highway Terrain (HT): Optimised for sealed roads - best on-road
- All-Terrain (AT): 50/50 on/off-road - popular for SUVs/4x4s
- Mud-Terrain (MT): Extreme off-road - reduced road grip
- High Performance (HP): Sporty tyres - better grip, faster wear
- Winter: Cold-weather compound - best below 7C
Research from TyreReviews, Tire Rack, and Wong (1993)
Tread Pattern
Tread Pattern Direction
The tread pattern affects water evacuation and grip characteristics.
- Symmetrical: Most common on economy tyres. Even wear, can be rotated any direction.
- Directional (V-pattern): Best water evacuation. Must be mounted correctly with arrow pointing forward.
- Asymmetrical: Different inner/outer tread for best all-round performance. Look for "OUTSIDE" marking.
- Asym-Directional: Combines both designs. Maximum performance but complex rotation.
Research from Continental, Kwik Fit UK, The AA
Tyre Pressure
Pressure Affects Contact Patch
Incorrect pressure changes how the tyre contacts the road, affecting grip and wear.
- Under-inflated: More rolling resistance, uneven wear, reduced grip
- Optimal (32 PSI): Full contact patch, best grip and fuel economy
- Over-inflated: Smaller contact patch, harsher ride, center wear
Check your door jamb sticker for recommended pressure. Check when tyres are cold.
Road Surface
Road Surface Types
Different road surfaces provide vastly different levels of grip. This has one of the largest impacts on stopping distance!
- Asphalt: Standard sealed roads - baseline grip
- Concrete: Highways, bridges - slightly lower wet grip
- Gravel: Unsealed NZ country roads - reduced grip
- Dirt: Farm tracks, off-road - low grip
- Mud: Wet earth - Very slippery!
- Grass: Paddocks, verges - Unpredictable grip
- Sand/Beach: Soft surface - Sinking risk
- Snow: Compacted snow - Winter tyres recommended
- Ice: Frozen surface - Extremely dangerous!
Trailer
Towing a Trailer?
Trailers significantly affect braking distance due to added weight and momentum. Trailer brakes (if fitted) help, but the tow vehicle still does most of the work.
- Unbraked trailer: Max 750kg in NZ - all braking from tow vehicle
- Braked trailer: Required over 750kg - has own braking system
Trailers can increase stopping distance by 20-50% depending on load!
Outside Air Temperature
Air Temperature & Tyre Grip
"Ambient temperature" means the outside air temperature - this affects both the road surface temperature and your tyre's rubber compound performance.
- Below 7°C: Summer tyres harden and lose grip. Winter tyres excel in cold. Road may be icy!
- 7-25°C: Optimal range for most summer/all-season tyres
- Above 30°C: Asphalt softens. Tyres heat up faster. Grip can actually improve slightly.
- Above 40°C: Extreme heat - risk of tyre overheating, reduced grip, increased wear
The 7°C threshold is why winter tyres are legally required in many European countries.
Check your car's outside temperature display or local weather forecast!
Wind Conditions
Wind & Braking
Wind affects braking distance through aerodynamic drag. A strong headwind helps slow you down, while a tailwind makes it harder to stop.
- Calm (0-15 km/h): Negligible effect
- Moderate (15-40 km/h): Slight effect on high-profile vehicles
- Strong (40-70 km/h): Noticeable effect, especially on trucks/trailers
- Severe (70+ km/h): Significant effect - can add/reduce several metres
Effect is more pronounced at higher vehicle speeds and on lighter vehicles with larger surface area.
ABS System
Anti-lock Braking System
ABS prevents wheel lock-up during emergency braking, allowing you to steer while braking.
- With ABS: Wheels pulse rapidly, maintaining traction. ~10-15% better braking on wet roads.
- Without ABS: Wheels can lock, leading to skidding and loss of steering control.
ABS is mandatory on all new vehicles sold in NZ since 2015.
Road Slope
Road Gradient & Braking
Road slope has a significant impact on braking distance due to gravity's effect on the vehicle.
- Uphill (+): Gravity helps slow the vehicle - shorter stopping distance
- Flat (0°): Normal braking conditions
- Downhill (-): Gravity works against braking - longer stopping distance
Common NZ Road Grades:
- ±2°: Typical highway
- ±5°: Hilly urban roads
- ±10°: Mountain passes (e.g., Rimutaka Hill)
- ±15°: Extreme grades (rare)
A 10° downhill can increase stopping distance by 50% or more!
Brake Condition
Brake Fade
Repeated or sustained hard braking generates heat in the brake system, causing "brake fade" - a significant loss of braking power.
- Cold/Normal (0-2): Full braking power available
- Warm (3-4): Slight reduction after spirited driving
- Hot (5-6): Noticeable fade - allow cooling time
- Very Hot (7-8): Significant fade - dangerous
- Severe Fade (9-10): Brake failure risk!
Common Causes:
- Long mountain descents (holding brakes)
- Repeated emergency stops
- Track/spirited driving
- Towing heavy loads downhill
Use engine braking on long descents. If brakes feel spongy, pull over and let them cool!
Tyre Compound Quality
Tyre Compound Types
Beyond the EU wet grip grade, tyre compounds vary significantly based on intended use and price point.
- Economy: Harder compound, longer life, ~12% less grip. Budget brands.
- Touring: Standard compound, balanced performance. Most OEM tyres.
- Performance: Softer compound, ~4-6% better grip, faster wear. Sport tyres.
- UHP (Ultra High Performance): Maximum grip, ~12% better dry grip. Premium sport.
- Track/Semi-Slick: Extreme dry grip (+25%), but POOR in wet (-15%)!
NZ Market Context:
Most tyres sold in NZ are Touring or Economy compounds. Performance/UHP are typically fitted to sports cars or as upgrades.
Track tyres are dangerous on wet roads - designed for dry circuits only!
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