Tire Ruler245/65R18 dimensions
| Overall diameter (height) | 30.54″ · 776 mm |
| Section width | 9.65″ · 245 mm |
| Sidewall height | 6.27″ · 159 mm |
| Wheel diameter | 18″ |
| Rim width (rule of thumb) | 7–8.5″ |
| Circumference | 95.9″ |
| Revolutions per mile | 660 |
| In inches (flotation style) | 30.5 × 9.6R18 |
How it’s calculated: the sidewall is 65% of the 245 mm width = 159.3 mm (6.27″). Add two sidewalls to the 18″ wheel: 18 + 2 × 6.27 = 30.54″.
Bigger tires than 245/65R18 on 18″ wheels
| Size | Height | Taller by | 60 mph reads |
|---|---|---|---|
| 275/60R18 | 31.0″ | +0.45″ (+1.5%) | 60.9 mph |
| 255/65R18 | 31.1″ | +0.51″ (+1.7%) | 61.0 mph |
| 265/65R18 | 31.6″ | +1.02″ (+3.4%) | 62.0 mph |
| 255/70R18 | 32.1″ | +1.52″ (+5.0%) | 63.0 mph |
| 275/65R18 | 32.1″ | +1.54″ (+5.0%) | 63.0 mph |
“60 mph reads” is your real speed when a speedometer set up for 245/65R18 shows 60. Above about 3% taller, most trucks need a leveling kit or lift, and the speedometer should be recalibrated.
Sizes equivalent to 245/65R18
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 |
|---|---|---|---|
| 265/60R18 | 30.5″ | 10.4″ | −0.1% |
| 275/60R18 | 31.0″ | 10.8″ | +1.5% |
Same height on a different wheel size
Changing wheel size (plus or minus sizing) while keeping the overall height keeps your speedometer right:
- 245/75R16: 30.5″ tall on a 16″ wheel (−0.2%)
- 265/70R16: 30.6″ tall on a 16″ wheel (+0.2%)
- 215/85R16: 30.4″ tall on a 16″ wheel (−0.5%)
- 245/70R17: 30.5″ tall on a 17″ wheel (−0.1%)
- 265/65R17: 30.6″ tall on a 17″ wheel (+0.1%)
- 265/50R20: 30.4″ tall on a 20″ wheel (−0.3%)
- 275/50R20: 30.8″ tall on a 20″ wheel (+0.9%)
- 265/45R21: 30.4″ tall on a 21″ wheel (−0.5%)
- 275/45R21: 30.7″ tall on a 21″ wheel (+0.7%)
- 265/40R22: 30.3″ tall on a 22″ wheel (−0.6%)
- 285/40R22: 31.0″ tall on a 22″ wheel (+1.4%)
Popular 245/65R18 comparisons
Frequently asked questions
Is 245/65R18 a 31 inch tire?
Not quite. 245/65R18 is 30.54 inches tall, between a 30 and a 31 inch tire.
What size is 245/65R18 in inches?
245/65R18 is 30.5 inches tall (overall diameter), 9.6 inches wide, with a 6.3 inch sidewall, and fits an 18 inch wheel.
What tire size is equivalent to 245/65R18?
Sizes within 1.5% of the same diameter on an 18" wheel: 265/60R18 (30.5"), 275/60R18 (31.0"). Check load index and width before swapping.
What rim width fits 245/65R18?
As a rule of thumb, about 7–8.5 inches. The tire maker's spec sheet lists the approved range for each model.
How many revolutions per mile does 245/65R18 make?
About 660 revolutions per mile in theory (circumference 95.9 in). Real tires turn slightly more because they flatten under load.