Tools / Everyday
Tyre size comparison
Going for bigger tyres? Enter the current and new sizes (e.g. 265/65R17 and 275/70R17) to see the difference in diameter and height, how the speedometer changes — your real speed when it shows 100 — and whether it's within reason.
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Current (width / aspect / rim)
New size
Example: 265/65R17 = width 265, aspect 65, rim 17
How to use it
- Enter the current size: width / aspect / rim (e.g. 265 / 65 / 17).
- Enter the new size.
- See the difference and the speedometer effect.
Questions
How do I read a size?
265/65R17: 265 mm wide, sidewall 65% of width, 17-inch rim — it's on the tyre's sidewall.
Why ±3%?
The usual guidance so speedometer, brakes and stability control aren't thrown off much. Beyond that, ask the dealer or tyre shop.
Will a bigger tyre rub?
This only compares sizes. Check wheel-arch clearance with the tyre shop, especially on full lock.