CAR
Tyre size calculator
Compare tyre sizes or enter your current size and choose a target rim diameter — the calculator will suggest the closest tyre sizes.
DIFFERENCE
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- Current tyre diameter
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- New tyre diameter
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- Circumference difference
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- Ground clearance change
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- Actual speed
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What does the result mean?
The smaller the difference in overall wheel diameter, the closer the speedometer reading and ground clearance will remain to the original. Suggestions are selected by overall wheel diameter, but before buying you should also check the vehicle manufacturer’s approved tyre sizes, rim width, offset (ET) and wheel-arch clearance.
How to choose an alternative tyre size
In 205/55 R16, 205 is tyre width in millimetres, 55 is sidewall height as a percentage of width, and R16 means a 16-inch rim. When increasing rim diameter, a lower tyre profile is usually chosen to keep the overall wheel diameter similar.
Changing from R16 to R17
For example, for 205/55 R16 the calculator can suggest R17 sizes with a similar overall diameter. The smaller the percentage difference, the smaller the change in speedometer reading and ground clearance. Click a suggestion to compare it directly with the current tyre.
What else should you check?
A similar overall diameter does not guarantee fitment. Check manufacturer-approved sizes, rim width and offset (ET), load and speed ratings, and available wheel-arch clearance.
Frequently asked questions
Can an R17 tyre fit an R16 rim?
No. Tyre and rim diameter must match: an R17 tyre requires an R17 rim.
Why use a lower profile with a larger rim?
It helps keep the overall wheel diameter close to the original when the rim diameter increases.