181Best 305/30 R21 tires
10 rated tires available in this size, scored on dry, wet, snow, comfort and wear. Top overall right now is the Continental ExtremeContact DWS 06 PLUS at 86/100.
28.2″
overall diameter
12″
section width
21″
rim diameter
715.1
revs per mile
Best 305/30 R21 summer tires
4181
280
374
474Best 305/30 R21 all-season tires
3
186
278
Best 305/30 R21 winter tires
2
183
More top-rated 305/30 R21 tires
1
190Conversion
305/30 R21 in inches
| Overall diameter | 28.2″ |
| Section width | 12″ |
| Rim diameter | 21″ |
| Sidewall height | 92 mm |
| Circumference | 88.6″ |
| Revolutions per mile | 715.1 |
Wheels
What rims fit 305/30 R21 tires?
A tire fits a range of rim widths. Too narrow or too wide and the sidewall changes shape.
Minimum
8.5″
Ideal
9.5″
Maximum
11″
Rim diameter is fixed at 21″ — only the width varies. Estimated from the 12″ section width (70–90% rule).
Fitted from the factory on rims: 21x11, 21x11.5.
Popular comparisons
Sizes often compared with 305/30 R21
Close alternatives — each opens in the tire size calculator.
Sidewall
305/30 R21 — what does it mean?
| Parameter | Meaning |
|---|---|
| 305 | The first number is the section width — 305 mm, or about 12 inches across the widest part of the tire. |
| 30 | The second number is the aspect ratio: sidewall height as a percentage of width. At 30%, the sidewall is about 92 mm tall. |
| R21 | R means radial construction, which nearly all modern tires use. The number is the rim diameter in inches — this tire fits a 21-inch wheel. |