Tire Ruler33x12.50R18 dimensions
| Overall diameter (height) | 33.00″ · 838 mm |
| Section width | 12.50″ · 318 mm |
| Sidewall height | 7.50″ · 191 mm |
| Wheel diameter | 18″ |
| Rim width (rule of thumb) | 9–11″ |
| Circumference | 103.7″ |
| Revolutions per mile | 611 |
33x12.50R18 is a flotation size: the first number is the height (33″), the second the width (12.5″) and the last the wheel (18″). The sidewall is (33 − 18) ÷ 2 = 7.50″. In metric terms it’s close to a 320/60R18.
Bigger tires than 33x12.50R18 on 18″ wheels
| Size | Height | Taller by | 60 mph reads |
|---|---|---|---|
| 295/70R18 | 34.3″ | +1.26″ (+3.8%) | 62.3 mph |
| 325/65R18 | 34.6″ | +1.63″ (+5.0%) | 63.0 mph |
| 285/75R18 | 34.8″ | +1.83″ (+5.5%) | 63.3 mph |
| 35x12.50R18 | 35.0″ | +2.00″ (+6.1%) | 63.6 mph |
“60 mph reads” is your real speed when a speedometer set up for 33x12.50R18 shows 60. Above about 3% taller, most trucks need a leveling kit or lift, and the speedometer should be recalibrated.
Sizes equivalent to 33x12.50R18
Within 1.5% of the same height on an 18″ wheel. Usually interchangeable for the speedometer; check width, load index and clearance.
| Size | Height | Width | Difference |
|---|---|---|---|
| 275/70R18 | 33.2″ | 10.8″ | +0.5% |
| 265/70R18 | 32.6″ | 10.4″ | −1.2% |
| 285/65R18 | 32.6″ | 11.2″ | −1.3% |
Same height on a different wheel size
Changing wheel size (plus or minus sizing) while keeping the overall height keeps your speedometer right:
- 33x12.50R15: 33.0″ tall on a 15″ wheel (±0.0%)
- 285/75R16: 32.8″ tall on a 16″ wheel (−0.5%)
- 285/70R17: 32.7″ tall on a 17″ wheel (−0.9%)
- 295/70R17: 33.3″ tall on a 17″ wheel (+0.8%)
- 255/80R17: 33.1″ tall on a 17″ wheel (+0.2%)
- 33x12.50R17: 33.0″ tall on a 17″ wheel (±0.0%)
- 275/60R20: 33.0″ tall on a 20″ wheel (−0.0%)
- 285/60R20: 33.5″ tall on a 20″ wheel (+1.4%)
- 305/55R20: 33.2″ tall on a 20″ wheel (+0.6%)
- 295/55R20: 32.8″ tall on a 20″ wheel (−0.7%)
- 265/60R20: 32.5″ tall on a 20″ wheel (−1.5%)
- 33x12.50R20: 33.0″ tall on a 20″ wheel (±0.0%)
- 305/45R22: 32.8″ tall on a 22″ wheel (−0.6%)
- 275/50R22: 32.8″ tall on a 22″ wheel (−0.5%)
- 33x12.50R22: 33.0″ tall on a 22″ wheel (±0.0%)
Popular 33x12.50R18 comparisons
Frequently asked questions
Is 33x12.50R18 a 33 inch tire?
Yes. 33x12.50R18 is 33.00 inches tall, so it's sold and talked about as a 33-inch tire.
What size is 33x12.50R18 in inches?
33x12.50R18 is 33.0 inches tall (overall diameter), 12.5 inches wide, with a 7.5 inch sidewall, and fits an 18 inch wheel.
What tire size is equivalent to 33x12.50R18?
Sizes within 1.5% of the same diameter on an 18" wheel: 275/70R18 (33.2"), 265/70R18 (32.6"), 285/65R18 (32.6"). Check load index and width before swapping.
What rim width fits 33x12.50R18?
As a rule of thumb, about 9–11 inches. The tire maker's spec sheet lists the approved range for each model.
How many revolutions per mile does 33x12.50R18 make?
About 611 revolutions per mile in theory (circumference 103.7 in). Real tires turn slightly more because they flatten under load.