Basics
How to read a tire sidewall
Every number on the tire tells you something. Learn to read 205/55 R16 and the load and speed indexes.
📅 Aug 17, 2026
✔ Free guide
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The size
- 205: section width in millimetres
- 55: aspect ratio — sidewall is 55% of the width
- R: radial construction
- 16: rim diameter in inches
Load and speed indexes
After the size you will see numbers like 91V. 91 is the load index (capacity) and V is the speed index (max certified speed). Never fit a tire with a lower load index than the original.
Other markings
- DOT code: the date — the last four digits are week and year (e.g. 2319 = week 23 of 2019)
- M+S: mud and snow rating
- Max load and pressure in PSI/kPa
Questions about this guide
Below 1.6 mm tread (many recommend 3 mm), if there are bulges, cuts or exposed cords, or after 6–10 years regardless of tread.
Avoid mixing across an axle and ideally keep all four matching. Different tread and compounds can upset handling.