Tire Ruler37x12.50R18 dimensions
| Overall diameter (height) | 37.00″ · 940 mm |
| Section width | 12.50″ · 318 mm |
| Sidewall height | 9.50″ · 241 mm |
| Wheel diameter | 18″ |
| Rim width (rule of thumb) | 9–11″ |
| Circumference | 116.2″ |
| Revolutions per mile | 545 |
37x12.50R18 is a flotation size: the first number is the height (37″), the second the width (12.5″) and the last the wheel (18″). The sidewall is (37 − 18) ÷ 2 = 9.50″. In metric terms it’s close to a 320/75R18.
Same height on a different wheel size
Changing wheel size (plus or minus sizing) while keeping the overall height keeps your speedometer right:
- 37x12.50R17: 37.0″ tall on a 17″ wheel (±0.0%)
- 37x12.50R20: 37.0″ tall on a 20″ wheel (±0.0%)
Frequently asked questions
Is 37x12.50R18 a 37 inch tire?
Yes. 37x12.50R18 is 37.00 inches tall, so it's sold and talked about as a 37-inch tire.
What size is 37x12.50R18 in inches?
37x12.50R18 is 37.0 inches tall (overall diameter), 12.5 inches wide, with a 9.5 inch sidewall, and fits an 18 inch wheel.
What tire size is equivalent to 37x12.50R18?
No common size on an 18" wheel is within 1.5% of 37x12.50R18's diameter. Use the calculator above to compare any size.
What rim width fits 37x12.50R18?
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 37x12.50R18 make?
About 545 revolutions per mile in theory (circumference 116.2 in). Real tires turn slightly more because they flatten under load.