9 March 2025
Best Tyres London: All-Season, Summer & Winter Guide
Choose the best tyres for London's weather: all-season, summer and winter options, EU tyre labels, pressure tips and top brands for safe driving.
Read the guide
In short
The markings on a tyre give its width in millimetres, the height of the sidewall as a percentage of that width (the aspect ratio) and the wheel rim diameter in inches, along with its load index and speed rating. Understanding tyre sizes and maintaining correct pressure is key to safety, performance and comfort.
Ever glanced at your tyres and wondered what those mysterious numbers and letters mean? You're not alone! Tyre sizes might seem complicated at first, but understanding them can significantly enhance your driving experience and safety.
On this page
Decoding Tyre Numbers and Letters
Each tyre has markings that reveal critical details about its dimensions:
Width (205)
The tyre's width in millimetres. Wider tyres provide increased road grip.
Aspect Ratio (55)
The height of the sidewall expressed as a percentage of the tyre's width. Lower ratios improve handling but offer a less cushioned ride.
Diameter (e.g., 16)
The wheel rim diameter in inches.
How Aspect Ratio Affects Driving
The aspect ratio greatly influences your driving experience:
Low Profile Tyres (e.g., 40-45)
Provide improved handling, sportier feel, but reduced ride comfort.
High Profile Tyres (e.g., 65-75)
Offer enhanced comfort by absorbing road shocks, but with softer handling characteristics.
Tyre Load and Speed Ratings
Load Index
Specifies the maximum load the tyre can support. For instance, an index of 91 means the tyre can handle up to 615 kg.
Speed Rating
Indicates the maximum safe speed for the tyre. A 'V' rating corresponds to 149 mph (240 km/h).
Importance of Correct Tyre Pressure
Maintaining proper tyre pressure is crucial:
Safety
Incorrect pressure affects braking distances and increases the risk of tyre failure.
Performance
Properly inflated tyres improve handling and responsiveness.
Fuel Efficiency
Under-inflated tyres can increase fuel consumption significantly.
Regularly check your vehicle’s recommended tyre pressures, typically found in your car’s owner manual, inside the driver’s door frame, or inside the fuel filler cap.
How to Find Your Vehicle’s Correct Tyre Information
Correct tyre specifications are vital. You can usually find this information in:
- The vehicle’s handbook
- A sticker located on the driver's door jamb
- Inside the fuel filler cap
- Manufacturer’s website
Special Tyre Markings
Tyres might also feature additional indicators:
XL (Extra Load)
For vehicles requiring higher load capacity.
M+S (Mud & Snow)
All-season tyres suitable for moderate winter conditions.
3PMSF (Three Peak Mountain Snowflake)
Certified for severe winter conditions.
When Should You Replace Your Tyres?
Replace tyres when you notice:
Tread Depth
Legally required minimum is 1.6 mm, but for best safety, replace at 3 mm.
Physical Damage
Cracks, bulges, or uneven wear indicate a replacement is essential.
Age
Replace tyres every 6-10 years regardless of tread condition.
Final Thoughts
Understanding tyre sizes and maintaining correct pressure isn't just about compliance—it's key to safety, performance, and comfort. Always adhere to your vehicle manufacturer's specifications to ensure a reliable and enjoyable driving experience.
