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Tire Size Comparison Calculator

Size 1



Size 2



Size 1Size 2Difference

Speedometer Error (Set Size1 to OEM Size):

Speed10 km/h20 km/h30 km/h50 km/h70 km/h90 km/h110 km/h130 km/h

Speedometer Error (Set Size2 to OEM Size):

Speed10 km/h20 km/h30 km/h50 km/h70 km/h90 km/h110 km/h130 km/h

Simplify your tyre selection process with a tyre size calculator for precise tyre size comparison. Easily compare tyre sizes to find the best fit for your vehicle, ensuring optimal performance and safety.

How does the tyre size comparison calculator work?

The tyre size calculator is a simple tool that does all the counting for you and helps you choose the best-fitting tyres for your vehicle. It works by taking measurements of two tyres and comparing tyre sizes: diameter, width, sidewall, circumference, and revolutions per kilometer. The calculator supports the Metric and Imperial systems for accurate tyre size comparison and provides the speedometer difference to ensure proper speed readings.

To use the tyre size calculator, simply enter the measurements of your current and potential tyres in the fields above. The tool will then instantly display a detailed comparison, helping you make an informed decision for your vehicle’s tyre selection.

How to interpret tyre code?

Tyre codes may look like a secret language, but once you know how to read it properly, it makes perfect sense. Each component of the tyre code has a different meaning and helps you choose the right tyres for your vehicle and unlock valuable insights like size, load capacity, and speed capabilities from a single digit.

Here’s a breakdown of how to interpret a typical tyre code:

Tyre type: The first letter indicates the tyre type and intended use:

  • P stands for Passenger vehicle.
  • LT is for Light Truck.
  • ST means Special Trailer.
  • T represents a Temporary (spare) tyre.
  • Width: The next three-digit number is the tyre width in millimeters, measured from sidewall to sidewall.

    Aspect ratio: The two-digit number following the slash is the aspect ratio of the tyre. It represents the height of the tyre’s cross-section as a percentage of its width. For example, an aspect ratio of 55 means the height is 55% of the width.

    Construction type: The letter that follows the aspect ratio indicates the tyre’s construction.

    • R stands for Radial construction.
    • B indicates Bias-ply construction.
    • D signifies Diagonal construction.

    Diameter: The next two-digit number is the diameter of the wheel rim in inches that the tyre fits.

    Load Index: The following number is the load index that indicates the maximum load the tyre can support. This number corresponds to a specific load capacity found in load index charts.

    Speed rating: The last letter of the tyre code is the speed rating. It represents the maximum speed the tyre can safely maintain. For instance, V corresponds to 149 mph (240 km/h).

    Let’s take the tyre code P215/60R17 96H for example:

    • P means that it’s Passenger vehicle
    • 215 – the width of the tyre is 215 mm
    • 60 – the aspect ratio of the tyre’s height to its width is 60%
    • R indicates Radial construction
    • 17 – the diameter of the wheel rim is 17 inches
    • 96 – the load index of 96 means that it can carry up to 710 kg per tyre
    • H – the maximum speed the tyre can safely maintain. H corresponds to a maximum speed of 130 mph (210 km/h).

    What size tyres will fit my car?

    The first thing you need to know before determining the right size tyres for your car is your original tyre measurements – you can’t calculate tyre size with alternative tyre sizes as that might lead you out of the safe limits for size differences.

    If you already have original tyre specifications, you need to know how much you can deviate from them. It’s easy if you follow the 3% tyre rule – the difference between your stock tyres and new ones should not exceed 3% in overall diameter to ensure safe and optimal performance. Larger deviations can affect your vehicle’s handling, speedometer accuracy, and fit within the wheel arch.

    Next, you should consider other factors like the space in the wheel arch and your specific car make and model – the tyre size calculator can’t account for that. These can impact the maximum tyre size that fits without rubbing or causing other issues. Refer to your vehicle’s manual to ensure compatibility and safety, and buy from a reliable store, like RRR, where you can find a variety of summer tires or winter tires, ensuring you get the perfect match for your vehicle.

    What else to consider when changing tyre sizes?

    When changing tyre sizes, there are several important factors to consider:

    Changing tyre sizes affects your car’s speedometer and odometer readings. Tyres with a larger diameter will cause the speedometer to show a lower speed than your actual speed, while tyres with a smaller diameter will show a higher speed. This can impact your driving and might require recalibration of these instruments.

    Consistency is the key – it’s crucial to change all tires at the same time, or at least in pairs (either the front two or the back two). If only one or two tyres are replaced, they should be the same brand and size as the existing ones to ensure balanced handling and performance.

    Changing tyre sizes might also necessitate changing the wheel size. Larger tyres may require larger wheels and vice versa, which can involve additional costs and considerations for fitment within the wheel arches.

    If you are choosing between wide and narrow tyres, here’s a summary of the pros and cons:

    • Wide tyres offer better grip and handling, especially in dry conditions. They can improve your car’s performance but may reduce fuel efficiency and increase road noise.
    • Narrow tyres typically provide better fuel efficiency and a smoother ride. They perform well in snowy or wet conditions due to higher contact pressure, but may not offer the same level of handling as wider tyres.

    Carefully considering these factors will help you make an informed decision when changing tyre sizes, ensuring safety, performance, and efficiency.