Decoded sidewall size
305/30R21 tire size
305/30R21 in inches: 28.20" overall diameter — 12.01" wide, 3.60" sidewall.
Methodology: dimensions are calculated from standard ETRTO tire-size formulas. Last reviewed June 2026 by the TreadSize editorial team.
Before you fit 305/30R21: 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 sizeFull dimensions
| Measurement | Metric | Imperial |
|---|---|---|
| Overall diameter | 716.4 mm | 28.20 in |
| Section width | 305 mm | 12.01 in |
| Sidewall height | 91.5 mm | 3.60 in |
| Rim diameter | 533.4 mm | 21 in |
| Circumference | 2250.6 mm | 88.61 in |
| Revolutions per mile | 715.1 | |
| Aspect ratio | 30% | |
NHTSA safety record for 305/30R21
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.
1 tire recall on record affecting 305/30R21
- NHTSA 26T011000 · 2026 GOODYEAR EAGLE F1 SUPERSPORT Tread separation increases the risk of a crash.
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.
Recall timeline for 305/30R21
NHTSA campaigns affecting this tire size, grouped from the local recall dataset. Exact owner-notification dates are not stored here; open the campaign at NHTSA for current remedy details.
How 305/30R21 compares inside the NHTSA size dataset
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
Dataset download: JSON or CSV. Latest recall lookup: NHTSA.gov.
Frequently asked questions
What is the overall diameter of a 305/30R21 tire?
A 305/30R21 tire has an overall diameter of 28.20 inches (716.4 mm).
How tall is a 305/30R21 tire?
The sidewall height is 91.5 mm (3.60 inches), and the overall diameter from the ground to the top of the tire is 28.20 inches.
How many revolutions per mile does a 305/30R21 tire make?
A 305/30R21 tire makes approximately 715 revolutions per mile. Your speedometer is calibrated to this number.
What rim size does a 305/30R21 tire fit?
A 305/30R21 tire is designed for a 21-inch rim (533.4 mm).
Are there recalls or safety complaints for 305/30R21 tires?
NHTSA has 0 consumer complaints on record for the 305/30R21 size and 1 recall. 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.