189Best 315/30 R21 tires
10 rated tires available in this size, scored on dry, wet, snow, comfort and wear. Top overall right now is the Michelin Pilot Sport 4 at 89/100.
28.4″
overall diameter
12.4″
section width
21″
rim diameter
709.1
revs per mile
Best 315/30 R21 summer tires
8189
283
383
480
579
676
776
874Best 315/30 R21 all-season tires
1
185Best 315/30 R21 winter tires
1
180Conversion
315/30 R21 in inches
| Overall diameter | 28.4″ |
| Section width | 12.4″ |
| Rim diameter | 21″ |
| Sidewall height | 95 mm |
| Circumference | 89.3″ |
| Revolutions per mile | 709.1 |
Wheels
What rims fit 315/30 R21 tires?
A tire fits a range of rim widths. Too narrow or too wide and the sidewall changes shape.
Minimum
8.5″
Ideal
10″
Maximum
11″
Rim diameter is fixed at 21″ — only the width varies. Estimated from the 12.4″ section width (70–90% rule).
Fitted from the factory on rims: 21x10.5, 21x11.5, 21x12.
Popular comparisons
Sizes often compared with 315/30 R21
Close alternatives — each opens in the tire size calculator.
Sidewall
315/30 R21 — what does it mean?
| Parameter | Meaning |
|---|---|
| 315 | The first number is the section width — 315 mm, or about 12.4 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 95 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. |