Tyre Size Calculator
Comparing 195/65R15 to 205/55R16? See exactly how diameter, sidewall, and speedo readings change before you buy.
Current tyre
Width (mm) / Aspect ratio (%) / Rim (inches)
New tyre
Diameter change
-0.41%
✅ Safe — within the recommended ±1.5% range
Industry rule: stay within ±3% diameter to keep speedo, ABS, traction control, and warranty intact. Always confirm load/speed ratings match your vehicle.
Things to know before changing tyre size
Stay within ±3% diameter
Outside this range, your speedometer, ABS, traction control, and even gear ratios stop working as designed. Many manufacturer warranties also become void.
Check load and speed ratings
A tyre size is more than just the dimensions. The two-character suffix (e.g. 91V) defines max load and max speed — never go below your vehicle’s required rating.
Wider isn’t always better
Wider tyres look great but can hurt fuel efficiency, cause rubbing on full lock, and may not pass annual inspection in some regions.
Get tyres fitted at a verified garage
Genuine brands, balancing and alignment included, with warranty.
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