These codes describe tested load capacity and speed capability; they are not optional decoration. The load index is a code that maps to a maximum load per tyre.
Tyre load index and speed rating is easier to understand when you separate the immediate decision from the checks behind it. These codes describe tested load capacity and speed capability; they are not optional decoration.
The large size numbers are only part of the decision. Construction, load capability, speed rating, seasonal design, vehicle approval and the way the car is used all influence whether a tyre is a sound match.
Short answer: These codes describe tested load capacity and speed capability; they are not optional decoration.
What you need to know
The important detail
The load index is a code that maps to a maximum load per tyre.
Check this point against both the fitted tyre and the vehicle handbook before building a shortlist.
What it means in practice
The speed symbol represents a test category, not permission to exceed legal limits.
Keep comparisons like-for-like; a cheaper product with a different specification is not a direct alternative.
What drivers often miss
Replacement specifications must satisfy the vehicle, axle load and relevant requirements.
Ask the retailer to confirm suitability in writing when the marking or vehicle requirement is unclear.
Do not downgrade a specification because a lower-rated tyre is cheaper.
A sensible check, step by step
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Copy the entire specification from the tyre and vehicle guidance.
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Compare products in the same size, load, speed and seasonal category.
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Confirm fitting, delivery and disposal costs before paying.
Common mistakes to avoid
- Relying on a single quick glance instead of checking the whole tyre and its inner edge.
- Using a generic number or internet tip when the vehicle handbook gives a specific requirement.
- Assuming a tyre is safe because no dashboard warning is showing.
What to do next
Check the complete tyre specification and condition in good light. Write down anything that differs between the four corners of the car. If the tyre may be unsafe, avoid unnecessary driving and arrange an inspection by a competent tyre professional.
Quick questions
Can I rely on a visual check?
No. A visual check is useful for obvious damage, but pressure, tread depth and internal condition may need the correct gauge or a professional inspection.
Should I check only before an MOT?
No. Tyres change between tests. Regular checks and a check before long journeys are a better routine.
What if I am still unsure?
Treat uncertainty about damage, fitment or pressure as a reason to ask a competent tyre professional before continuing a journey.
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