193Best 235/40 R18 tires
131 rated tires available in this size, scored on dry, wet, snow, comfort and wear. Top overall right now is the Michelin Pilot Sport PS2 at 93/100.
25.4″
overall diameter
9.3″
section width
18″
rim diameter
794
revs per mile
Best 235/40 R18 summer tires
62193
293
389
489
586
684
784
889
983
1083
1182
128250 more rated tires in this size are listed on their brand pages.
More top-rated 235/40 R18 tires
31
192
288
388
490
588
687
784
883
984
1083
1183
129319 more rated tires in this size are listed on their brand pages.
Best 235/40 R18 all-season tires
28
189
288
391
486
586
685
784
884
982
1087
1184
128716 more rated tires in this size are listed on their brand pages.
Best 235/40 R18 winter tires
10
183
280
379
478
578
676
776
875
1074Conversion
235/40 R18 in inches
| Overall diameter | 25.4″ |
| Section width | 9.3″ |
| Rim diameter | 18″ |
| Sidewall height | 94 mm |
| Circumference | 79.8″ |
| Revolutions per mile | 794 |
The closest flotation size is 28x12.00R18 — 10.2% taller and 29.7% wider. Compare them in the calculator.
Wheels
What rims fit 235/40 R18 tires?
A tire fits a range of rim widths. Too narrow or too wide and the sidewall changes shape.
Minimum
6.5″
Ideal
7.5″
Maximum
8.5″
Rim diameter is fixed at 18″ — only the width varies. Estimated from the 9.3″ section width (70–90% rule).
Fitted from the factory on rims: 18x7.5, 18x8, 18x8.3, 18x8.5, 18x9, 18x10, 18x10.5, 18x11, 18x12.
Popular comparisons
Sizes often compared with 235/40 R18
Close alternatives — each opens in the tire size calculator.
Sidewall
235/40 R18 — what does it mean?
| Parameter | Meaning |
|---|---|
| 235 | The first number is the section width — 235 mm, or about 9.3 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 94 mm tall. |
| R18 | R means radial construction, which nearly all modern tires use. The number is the rim diameter in inches — this tire fits a 18-inch wheel. |