Ride & comfort
Tire sidewall height explained
Sidewall height is a percentage of tire width. Equal profile numbers can hide meaningful differences in height.
Convert the percentage into millimetres
For 225/45 R17, sidewall height is 225 × 45 ÷ 100 = 101.25 mm. For 235/45 R17 it is 105.75 mm. Both are “45 profile,” but the wider tire has 4.5 mm more sidewall on each side of the wheel.
Understand why two sidewalls count
Outside diameter spans the lower sidewall, the wheel and the upper sidewall. A 4.5 mm increase in sidewall therefore adds 9 mm to overall diameter when the wheel diameter is unchanged. Radius and theoretical ride height rise by 4.5 mm.
Use height as context, not a rating
A larger sidewall provides more geometric space for deflection, but stiffness depends on construction and inflation. A tire’s load rating or reinforced specification cannot be derived from this height. Use physical dimensions to compare configurations and manufacturer data to evaluate suitability.
Method and references
Examples use nominal geometry and fixed-price scenarios, with no vehicle-specific specifications implied. See our calculation methodology and editorial policy.
Dimension reference: Tire Rack: calculating tire dimensions. Consult the tire and vehicle manufacturers for actual fitment requirements.