TreadSize

Decoded sidewall size

275/40R18 tire size

275/40R18 in inches: 26.66" overall diameter — 10.83" wide, 4.33" sidewall.

Methodology: dimensions are calculated from standard ETRTO tire-size formulas. Last reviewed June 2026 by the TreadSize editorial team.

275/40R18 tire detail photo with TreadSize diameter, width, and rim measurement card
Overall diameter 26.66 in 677.2 mm
Section width 10.83 in 275 mm
Sidewall height 4.33 in 110 mm
Revs / mile 756 speedo calibration

Before you fit 275/40R18: verify the vehicle placard, load index, speed rating, wheel offset, and full-lock/full-compression clearance. Nominal dimensions do not guarantee a safe physical fit.

Compare this size

Full dimensions

Measurement Metric Imperial
Overall diameter 677.2 mm 26.66 in
Section width 275 mm 10.83 in
Sidewall height 110 mm 4.33 in
Rim diameter 457.2 mm 18 in
Circumference 2127.5 mm 83.76 in
Revolutions per mile 756.5
Aspect ratio 40%

NHTSA safety record for 275/40R18

Drawn from official U.S. government (NHTSA) consumer complaint and recall filings for this exact tire size — not the generic averages you'll find elsewhere.

Complaints on record 7 filed with NHTSA
Recalls on record 0 none on record

What owners report fails — 275/40R18

  • Tread separation 2
  • Road hazard 2
  • Cracking 1

These are unverified consumer reports and manufacturer recalls filed with the National Highway Traffic Safety Administration — not validated failure rates, and not adjusted for how many tires of this size are in service. Popular sizes naturally accumulate more reports. Use this as a research signal, not a verdict on any specific tire. Data as of 2021. Source: NHTSA Office of Defects Investigation (public domain). Always check the latest recalls at NHTSA.gov and report a tire problem if you have one.

How 275/40R18 compares inside the NHTSA size dataset

Complaint rank #156 of 271 among 271 safety-record sizes
Vs dataset median 3 below median 10 complaints
Top failure share 29% Tread separation

This comparison is derived only from tire sizes that have a real NHTSA complaint or recall record in the TreadSize dataset. Source: NHTSA ODI — Consumer Complaints (FLAT_CMPL) + Recalls (FLAT_RCL), U.S. DOT public domain; Complaints through 2021.

Nearby safety records by complaint volume

255/55R18 7 complaints · 3 recalls 255/70R22 7 complaints · 2 recalls 265/50R20 7 complaints · 2 recalls 275/70R16 7 complaints · 1 recalls 205/55R15 7 complaints · 0 recalls 225/70R18 7 complaints · 0 recalls 225/80R22 7 complaints · 0 recalls 235/55R16 7 complaints · 0 recalls

Dataset download: JSON or CSV. Latest recall lookup: NHTSA.gov.

Related tire sizes

255/40R18 → 275/35R18 → 275/40R19 →
Decode another tire size →  ·  Compare two sizes →  ·  Plus sizing →

Frequently asked questions

What is the overall diameter of a 275/40R18 tire?

A 275/40R18 tire has an overall diameter of 26.66 inches (677.2 mm).

How tall is a 275/40R18 tire?

The sidewall height is 110 mm (4.33 inches), and the overall diameter from the ground to the top of the tire is 26.66 inches.

How many revolutions per mile does a 275/40R18 tire make?

A 275/40R18 tire makes approximately 756 revolutions per mile. Your speedometer is calibrated to this number.

What rim size does a 275/40R18 tire fit?

A 275/40R18 tire is designed for a 18-inch rim (457.2 mm).

Are there recalls or safety complaints for 275/40R18 tires?

NHTSA has 7 consumer complaints on record for the 275/40R18 size; the most reported issue is tread separation (2 reports). These are unverified consumer reports, not validated failure rates, and are not adjusted for how many tires of this size are in service.

All dimensions calculated using standard ETRTO formulas. Always confirm fitment with your vehicle's door-placard and a qualified tire professional before purchasing.