Best 315/25 R21 tires
We don't have rated tires listed in this size yet — the conversion, rim fitment and comparisons below still apply.
27.2″
overall diameter
12.4″
section width
21″
rim diameter
741.5
revs per mile
Conversion
315/25 R21 in inches
| Overall diameter | 27.2″ |
| Section width | 12.4″ |
| Rim diameter | 21″ |
| Sidewall height | 79 mm |
| Circumference | 85.5″ |
| Revolutions per mile | 741.5 |
Wheels
What rims fit 315/25 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: 21x11.5.
Sidewall
315/25 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. |
| 25 | The second number is the aspect ratio: sidewall height as a percentage of width. At 25%, the sidewall is about 79 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. |