235/40R18 is a tire size notation. It describes geometry but does not establish the load, speed, tire class, wheel approval or fit of a particular replacement.
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How to read this size
- Nominal width: 235 mm
- Aspect ratio: 40 %
- Wheel diameter: 18.0 in
- Calculated nominal diameter: 645.2 mm
Calculated nominal diameter is an arithmetic estimate from the size code; actual product measurements vary.
Before ordering tires
Read the driver-door tire placard. Match the installed wheel, axle, tire class, load index, speed rating and any OE marking. The size alone cannot approve a replacement SKU. Tire-sidewall maximum pressure is not your vehicle’s cold inflation pressure.
Vehicles recorded with this size
| Model year and vehicle | Trim / option | Axle | Service |
|---|---|---|---|
| 2025 Acura Integra | A-Spec | front_rear | 91W |
| 2025 Acura Integra | A-Spec with Technology (6MT) | front_rear | 91W |
| 2025 Acura Integra | A-Spec with Technology (CVT) | front_rear | 91W |
| 2018 Ford Focus | ST | unspecified | Not documented |
| 2018 Ford Focus | Titanium with Handling Package | unspecified | Not documented |
| 2025 Honda Civic | Hybrid Sport Hatchback | front_rear | Not documented |
| 2025 Honda Civic | Hybrid Sport Sedan | front_rear | Not documented |
| 2025 Honda Civic | Hybrid Sport Touring Hatchback | front_rear | Not documented |
| 2025 Honda Civic | Hybrid Sport Touring Sedan | front_rear | Not documented |
| 2025 Honda Civic | Si | front_rear | Not documented |
| 2025 Honda Civic | Sport Hatchback | front_rear | Not documented |
| 2025 Honda Civic | Sport Sedan | front_rear | Not documented |
| 2025 Honda Civic Sedan | Sport | front_rear | 91W |
| 2025 Honda Civic Sedan | Sport Hybrid | front_rear | 91W |
| 2025 Honda Civic Sedan | Sport Touring Hybrid | front_rear | 91W |
| 2025 Hyundai Elantra | N Line | front_rear | Not documented |
| 2025 Kia K4 | GT-Line | front_rear | Not documented |
| 2025 Kia K4 | GT-Line Turbo | front_rear | Not documented |
| 2006 Pontiac GTO | Summer Only | unspecified | Not documented |
| 2025 Toyota GR Corolla | Core | unspecified | Not documented |
| 2025 Toyota GR Corolla | Premium | unspecified | Not documented |
| 2025 Toyota GR Corolla | Premium Plus | unspecified | Not documented |
Exact product variants in research
| Tire line | Manufacturer part number | Service |
|---|---|---|
| Kumho TA91 | 6301192 | 91W |
Explore 235/40R18 tires on Amazon
Amazon search results may mix tire classes, load and speed ratings, OE markings and package quantities. Match the full requirement on your actual vehicle before ordering.
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Search 235/40R18 tires on AmazonCompare sizes with the tire size calculator. It is an educational geometry comparison, not a fitment ruling.
Sources and scope
- American Honda — 2025 Civic Sedan Specifications & Features (checked 2026-11-01)
- American Honda / Acura — 2025 Acura Integra Specifications & Features (checked 2026-11-01)
- Goodyear — 2025 Hyundai Elantra tire size by version (checked 2026-11-01)
- Kia America — 2025 Kia K4 Specifications (checked 2026-11-01)
- Goodyear — 2025 Honda Civic tire size by version (checked 2026-11-01)
- Goodyear — Find 2018 Ford Focus Tires | Goodyear (checked 2026-11-01)
- Goodyear — Find 2025 Toyota GR Corolla Tires | Goodyear (checked 2026-11-01)
- Goodyear — Find 2006 Pontiac GTO Tires | Goodyear (checked 2026-11-01)
- Kumho Tire USA — Original Equipment — selected Hyundai and Kia product-code rows (checked 2026-11-01)
Research checked November 2, 2026. A source-observed size is not final product fitment. Confirm the actual vehicle and current manufacturer guidance.