235/40R18 Tire Size in Inches

A 235/40R18 tire is about 25.4 inches tall and 9.25 inches wide, with a 3.7-inch sidewall, fitted to a 18-inch wheel.

Source: manufacturer documents (listed below) · Updated 2026-11-05 · By CarWhere Research

Overall diameter
25.4 in
Section width
9.25 in
Sidewall height
3.7 in
Revolutions / mile
794

Calculated nominal dimensions; circumference 79.8 in. Measured size varies slightly by tire model and rim width.

Vehicles with factory 235/40R18 tires

Vehicles fitted with 235/40R18 tires from the factory
VehicleTrimYears
Honda CivicSport2022, 2023, 2024, 2025, 2026[1],[3],[5],[7],[9]
Honda CivicTouring2022, 2023, 2024[1],[3],[5]
Honda CivicSi2022, 2023, 2024, 2025, 2026[2],[4],[6],[8],[10]
Honda CivicSi HPT2022[2]
Honda CivicSport (Hybrid)2025[7]
Honda CivicSport Touring (Hybrid)2025[7]
Honda CivicSport Hybrid2026[9]
Honda CivicSport Touring Hybrid2026[9]

Compared with nearby sizes

235/40R18 compared with nearby sizes
SizeDiameterDifference
235/40R1825.4 in—
235/35R1824.5 in-3.5%
235/45R1826.3 in+3.5%

Width in inches

235 tire size in inches

Check the exact vehicle, not just the model

Trim, package and production changes all move these numbers. Decode the 17-character VIN with the free VIN decoder to confirm the engine and trim, or see the federal engine and MPG specs. Shopping? Browse live inventory and what buyers actually paid.

Frequently asked questions

How tall is a 235/40R18 tire in inches?

About 25.4 inches: a 18-inch wheel plus two 3.7-inch sidewalls (235 × 40% = 94 mm each).

How wide is a 235/40R18 tire?

9.25 inches of section width (235 mm ÷ 25.4).

What vehicles come with 235/40R18 tires?

In our manufacturer-sourced data: Honda Civic — trims and years are in the table above.

Sources

  1. American Honda Motor Co., Inc. (hondanews.com), 2022 Civic Sedan Specifications & Features, Specifications table, Wheels and Tires rows (accessed 2026-11-05).
  2. American Honda Motor Co., Inc. (hondanews.com), 2022 Civic Si Specifications & Features, Specifications table, Wheels and Tires rows (accessed 2026-11-05).
  3. American Honda Motor Co., Inc. (hondanews.com), 2023 Honda Civic Sedan Specifications & Features, Specifications table, Wheels and Tires rows (accessed 2026-11-05).
  4. American Honda Motor Co., Inc. (hondanews.com), 2023 Honda Civic Si Specifications & Features, Specifications table, Wheels and Tires rows (accessed 2026-11-05).
  5. American Honda Motor Co., Inc. (hondanews.com), 2024 Honda Civic Sedan Specifications & Features, Specifications table, Wheels and Tires rows (accessed 2026-11-05).
  6. American Honda Motor Co., Inc. (hondanews.com), 2024 Honda Civic Si Specifications & Features, Specifications table, Wheels and Tires rows (accessed 2026-11-05).
  7. American Honda Motor Co., Inc. (hondanews.com), 2025 Honda Civic Sedan Specifications & Features, Specifications table, Wheels and Tires rows (accessed 2026-11-05).
  8. American Honda Motor Co., Inc. (hondanews.com), 2025 Honda Civic Si Specifications & Features, Specifications table, Wheels and Tires rows (accessed 2026-11-05).
  9. American Honda Motor Co., Inc. (hondanews.com), 2026 Honda Civic Sedan Specifications & Features, Specifications table, Wheels and Tires rows (accessed 2026-11-05).
  10. American Honda Motor Co., Inc. (hondanews.com), 2026 Honda Civic Si Specifications & Features, Specifications table, Wheels and Tires rows (accessed 2026-11-05).