Tire Size and Speed Rating Reference
Decode tire size markings load index and speed rating codes in a searchable reference table.
A tire code like 225/45R17 91V breaks down as: 225 = section width (mm), 45 = aspect ratio (%), R = radial construction, 17 = wheel diameter (in), 91 = load index, V = speed rating.
Speed rating
Load index (common range)
About this tool
Tire Size and Speed Rating Reference is a single-purpose utility on instant.tw, a free toolbox of calculators, converters, generators, and quick lookups. Everything works in your browser — nothing is uploaded, nothing is stored on a server unless explicitly noted.
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