How to read a metric radial tire size
Understand width, aspect ratio, radial construction, and rim diameter before using a nominal tire calculator.
Read articleGeometry without a fitment verdict
Tire size guides
Read a metric radial code, derive the speed ratio, and understand why nominal geometry does not approve fitment.
How nominal tire diameter affects a theoretical speedometer reading
Derive the exact diameter ratio, see why pi cancels, and understand what the estimate cannot predict.
Read articleWhy equal nominal diameter does not prove tire fitment
A close diameter is only one geometric comparison; safe replacement requires vehicle, wheel, rating, clearance, and legal checks.
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