305/55R20 Tire Size Specifications
Complete dimensional breakdown in inches and millimeters, approved wheel rim widths, vehicle fitments, speedometer error tables, and safe plus-sizing alternatives.
305/55R20 Technical Dimension Table
Standardized measurements computed according to ETRTO & ISO 4000-1 passenger and commercial tire design formulas.
| Specification Property | Imperial (Inches / Miles) | Metric (Millimeters / Kilometers) |
|---|---|---|
| Overall Rolling Diameter | 33.21 in | 843.5 mm |
| Section Width (Cross-section) | 12.01 in | 305 mm |
| Sidewall Cushion Height | 6.6 in | 167.6 mm |
| Circumference (Rolling Distance) | 104.33 in | 2650 mm |
| Revolutions per Distance | 626 revs/mile | 389 revs/km |
| Wheel Rim Diameter | 20 in | 508.0 mm |
| Approved Rim Width Range | 8.2" – 10.7" | 208 – 272 mm |
| Measuring / Ideal Rim Width | 9.4 in | 239 mm |
| Aspect Ratio (Profile %) | 55% of section width | |
What 305/55R20 Is Typically Used For
Dimensions in this range are typical of pickups, SUVs and off-road fitments, where load capacity and sidewall strength matter more than steering response.
To find the size your specific vehicle takes, check the placard on the driver-side door jamb or your owner's manual. Fitment depends on model year, trim, brake caliper clearance, wheel offset and suspension setup, so the correct size for your car is the one the manufacturer specifies.
Popular Comparisons with 305/55R20
Frequently Asked Questions about 305/55R20
What size is 305/55R20 in inches?
The 305/55R20 tire measures approximately 33.21" in overall diameter, 12.01" in section width (tread/sidewall cross-section), and is mounted on a 20" diameter wheel rim.
What rim width is recommended for 305/55R20?
The approved rim width range for 305/55R20 is 8.2" to 10.7" wide, with an ideal measuring rim width of 9.4" for optimal tread contact and even wear.
What are the closest safe alternative sizes for 305/55R20?
Always verify rolling diameter stays within ±3% of 33.21" to prevent transmission strain and speedometer inaccuracies.
How many revolutions per mile does 305/55R20 make?
A standard 305/55R20 tire rotates approximately 626 revolutions per mile (389 revs per kilometer) at normal inflation pressure and rolling radius.