The wet-grip grade on a tyre label describes performance in a defined wet assessment. It helps compare suitable tyres, but it is not a complete wet-weather score and does not tell you an exact stopping distance for your car.
Read the scale on the actual label
The EU/Northern Ireland label uses grades from A to E for wet grip. Great Britain has a different regulatory framework, so check the scale shown rather than assuming every label has the same format. In either case, compare the exact tyre version, not a headline grade for an entire range.
Size, load specification and original-equipment variants can affect the applicable product information. If two listings disagree, ask for the product identifier and manufacturer information.
What the grade does not measure
Wet braking is not the same as aquaplaning resistance or wet cornering. A high grade does not mean the tyre leads every wet-road test. It also does not describe dry grip, cabin noise or lifespan.
Use relevant independent comparisons to investigate those qualities where evidence is available. Keep the tested model, size and conditions attached to any result.
Is there a fixed stopping-distance gap between letters?
No universal number of metres can be applied to every pair of grades on every vehicle. A published demonstration can illustrate a difference under its own conditions, but it should not become a promise that each grade adds one car length or that the best and worst always differ by 18 metres.
Grades group products into bands. Two tyres inside one band can still produce different results in another described test.
How to use the rating when buying
First confirm the approved fitment. Compare the actual labels, then examine the wider evidence and complete fitted price. If rain is a major concern, give aquaplaning and wet-handling evidence attention too.
After fitting, maintain the recommended pressures and inspect tread and condition. A label on a new tyre does not establish the performance of a worn, damaged or incorrectly inflated one.