Tire Size Calculator

Tire Size Calculator uses a clear formula, labeled inputs, official references, and a shareable result URL for checking a scenario. The calculator evaluates the displayed relationship Diameter = rim + 2 × width × aspect ÷ 100 ÷ 25.4; it does not insert an undisclosed rate, conversion, forecast, or adjustment. Its input set is width, aspect, and rim. The worked starting scenario uses width = 225, aspect = 55, and rim = 17, which is only an editable example and not a recommendation. Enter each quantity in the unit printed beside its field, because a correct equation still produces a misleading result when units or percentage conventions are mixed. To understand sensitivity, hold every field except one constant and compare the new output with the baseline. That makes the effect of width visible without confusing it with a simultaneous change to rim. The result is rounded for display after the calculation, so small differences from another tool can come from precision, input definitions, or a different formula. This page is a focused model of Diameter = rim + 2 × width × aspect ÷ 100 ÷ 25.4, not a substitute for missing eligibility rules, taxes, fees, clinical judgment, building requirements, or contractual terms. Only the values shown are included. For verification, the method and terminology are checked against Tire and Rim Association standards from The Tire and Rim Association; review that source for definitions, limits, and exceptions that may apply outside this simplified calculation. The server-rendered GET form keeps a completed scenario reviewable from its URL, including when JavaScript is unavailable.