184Best 315/40 R21 tires
23 rated tires available in this size, scored on dry, wet, snow, comfort and wear. Top overall right now is the Nokian Hakkapeliitta R5 SUV at 88/100.
30.9″
overall diameter
12.4″
section width
21″
rim diameter
652.2
revs per mile
Best 315/40 R21 summer tires
11184
283
387
482
577
677
776
876
974
1071
1170More top-rated 315/40 R21 tires
6
188
285
386
488
588
674Best 315/40 R21 all-season tires
4
177
362
465Best 315/40 R21 winter tires
2
185
281Conversion
315/40 R21 in inches
| Overall diameter | 30.9″ |
| Section width | 12.4″ |
| Rim diameter | 21″ |
| Sidewall height | 126 mm |
| Circumference | 97.1″ |
| Revolutions per mile | 652.2 |
Wheels
What rims fit 315/40 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, 21x11.5.
Sidewall
315/40 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. |
| 40 | The second number is the aspect ratio: sidewall height as a percentage of width. At 40%, the sidewall is about 126 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. |