178Best 255/30 R21 tires
5 rated tires available in this size, scored on dry, wet, snow, comfort and wear. Top overall right now is the Atlas Force UHP at 84/100.
27″
overall diameter
10″
section width
21″
rim diameter
746.3
revs per mile
Best 255/30 R21 summer tires
3178
270
353More top-rated 255/30 R21 tires
1
184Best 255/30 R21 all-season tires
1
184Conversion
255/30 R21 in inches
| Overall diameter | 27″ |
| Section width | 10″ |
| Rim diameter | 21″ |
| Sidewall height | 77 mm |
| Circumference | 84.9″ |
| Revolutions per mile | 746.3 |
Wheels
What rims fit 255/30 R21 tires?
A tire fits a range of rim widths. Too narrow or too wide and the sidewall changes shape.
Minimum
7″
Ideal
8″
Maximum
9″
Rim diameter is fixed at 21″ — only the width varies. Estimated from the 10″ section width (70–90% rule).
Fitted from the factory on rims: 21x9, 21x9.5, 21x11, 21x13.
Popular comparisons
Sizes often compared with 255/30 R21
Close alternatives — each opens in the tire size calculator.
Sidewall
255/30 R21 — what does it mean?
| Parameter | Meaning |
|---|---|
| 255 | The first number is the section width — 255 mm, or about 10 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 77 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. |