Herramientas prácticas para trabajos de precisión
Calculadora de Comparación de Tamaños de Neumático
Compare dos tamaños de neumático lado a lado: diámetro, flanco, circunferencia y efecto en el velocímetro.
e.g. 225/45R18
e.g. 245/40R18
Cómo funciona
Reading a tire size: in 225/45R18, 225 is nominal section width in millimetres, 45 is sidewall height as a percentage of width, R means radial construction, and 18 is wheel diameter in inches.
Each tyre's overall diameter = wheel diameter + 2 × (section width × aspect ratio). The speed error assumes tyre B is fitted but the speedometer remains calibrated for tyre A - actual speed = indicated speed × (diameter B ÷ diameter A).
Worked example: the starting 225/45R18 tire is 659.7 mm in diameter. The proposed 245/40R18 is 653.2 mm, a 6.5 mm or 0.99% reduction, and its circumference is about 20.4 mm shorter. With the speedometer still calibrated for tire A, an indicated 60 mph corresponds to about 59.41 mph. These are geometric comparisons, not a fitment approval.
A diameter change within about 3% is a common screening reference, not a universal fitment rule. Load rating, wheel width and offset, brake clearance, suspension clearance and the vehicle manufacturer's approved sizes still need to be checked.
Tyre dimensions are nominal. Measure the fitted tyre when clearance is close because rim width, pressure, load and manufacturer construction change the real section width and diameter.
Preguntas frecuentes
Why do the wheel diameters need to match?
What does a larger tire do to the speedometer?
Does a diameter difference under 3% guarantee the tire will fit?
Herramientas relacionadas
Calculadora de Offset
Compare una configuración actual y propuesta de rueda/neumático y vea exactamente cómo cambia la geometría.
Calculadora de Separadores
Vea cómo un separador de rueda cambia su offset efectivo y cuánto se desplaza la rueda hacia afuera.
Neumáticos Alternativos
Encuentre tamaños de neumático estándar, incluidos distintos diámetros de rueda, que mantengan el diámetro total dentro de una tolerancia elegida respecto al tamaño original.
Radio de Pivote
Vea cuánto desplaza su radio de pivote (scrub radius) un cambio de offset de rueda o separador, respecto a un valor base conocido.