Updated October 2026 · Reviewed by NTW Tire Specialists
Quick version: revolutions per mile is how many times a tire turns in one mile. Going by the tire makers' published figures, a 33" tire turns about 620-640 times a mile, a 35" about 590-605, a 37" about 560-575 and a 40" about 520. Bigger tires turn fewer times, which makes your speedometer read low and your gears act taller. The charts below give the math for any height, the tire makers' published figures for the tires we sell, and the gear ratio that restores stock performance.
How to Calculate Revolutions Per Mile
Revolutions per mile = 63,360 ÷ (tire diameter × 3.1416). 63,360 is the number of inches in a mile, and diameter × 3.1416 is the tire's rollout, the distance it covers in one turn. A 35" tire rolls out about 110" per turn, so it turns about 576 times a mile.
Tire makers publish their own figure, measured with the tire loaded on a vehicle. A loaded tire flattens slightly at the bottom and rolls a little shorter than its height, so the published number usually runs 2-4% higher than the math. Use the published figure for speedometer calibration when you have it.
Diameter, Rollout and Revolutions Per Mile Chart
Calculated from tire height, for drivetrain math. Find your tire's real height on its spec sheet or with our tire size calculator.
| Tire diameter | Rollout (circumference) | Revolutions per mile |
|---|---|---|
| 26" | 81.7" | 776 |
| 26.5" | 83.3" | 761 |
| 27" | 84.8" | 747 |
| 27.5" | 86.4" | 733 |
| 28" | 88.0" | 720 |
| 28.5" | 89.5" | 708 |
| 29" | 91.1" | 695 |
| 29.5" | 92.7" | 684 |
| 30" | 94.2" | 672 |
| 30.5" | 95.8" | 661 |
| 31" | 97.4" | 651 |
| 31.5" | 99.0" | 640 |
| 32" | 100.5" | 630 |
| 32.5" | 102.1" | 621 |
| 33" | 103.7" | 611 |
| 33.5" | 105.2" | 602 |
| 34" | 106.8" | 593 |
| 34.5" | 108.4" | 585 |
| 35" | 110.0" | 576 |
| 35.5" | 111.5" | 568 |
| 36" | 113.1" | 560 |
| 36.5" | 114.7" | 553 |
| 37" | 116.2" | 545 |
| 37.5" | 117.8" | 538 |
| 38" | 119.4" | 531 |
| 38.5" | 121.0" | 524 |
| 39" | 122.5" | 517 |
| 39.5" | 124.1" | 511 |
| 40" | 125.7" | 504 |
| 40.5" | 127.2" | 498 |
| 41" | 128.8" | 492 |
| 41.5" | 130.4" | 486 |
| 42" | 131.9" | 480 |
| 42.5" | 133.5" | 475 |
| 43" | 135.1" | 469 |
| 43.5" | 136.7" | 464 |
| 44" | 138.2" | 458 |
| 44.5" | 139.8" | 453 |
| 45" | 141.4" | 448 |
| 45.5" | 142.9" | 443 |
| 46" | 144.5" | 438 |
Published Revolutions Per Mile for Popular Off-Road Tires
The tire maker's own figure for tires we stock, next to the calculated value for the same height. Tread pattern, construction and load range all move the real number, which is why two "35s" can differ by 20 revolutions a mile.
Bigger Tires and Your Gearing
Going up in tire size makes your axle ratio act taller. To get the stock feel back, multiply your current ratio by new tire height ÷ old tire height. The table assumes a stock 31.6" tire (265/70R17 and similar); pick the nearest available ratio, usually 3.73, 4.10, 4.30, 4.56, 4.88, 5.13 or 5.38.
| Stock axle ratio | On 33s | On 35s | On 37s | On 40s |
|---|---|---|---|---|
| 3.21 | 3.35 | 3.56 | 3.76 | 4.06 |
| 3.55 | 3.71 | 3.93 | 4.16 | 4.49 |
| 3.73 | 3.90 | 4.13 | 4.37 | 4.72 |
| 3.92 | 4.09 | 4.34 | 4.59 | 4.96 |
| 4.10 | 4.28 | 4.54 | 4.80 | 5.19 |
Speedometer Error on Bigger Tires
Until it is recalibrated, your speedometer reads low by the same percentage the tire grew. Compared with a stock 31.6" tire:
| New tire | Speedometer error | Actual speed at an indicated 60 | Actual speed at an indicated 70 |
|---|---|---|---|
| 33" | +4.4% | 62.7 mph | 73.1 mph |
| 35" | +10.8% | 66.5 mph | 77.5 mph |
| 37" | +17.1% | 70.3 mph | 82.0 mph |
| 40" | +26.6% | 75.9 mph | 88.6 mph |
Revolutions Per Mile FAQ
What does revolutions per mile mean?
It is how many times a tire turns to roll one mile. Bigger tires turn fewer times: a 31" tire turns about 660-680 times a mile, a 35" about 590-605, and a 37" about 560-575 (tire makers' published figures). Your speedometer, odometer, transmission shift points and effective gearing all depend on this number.
How do I calculate revolutions per mile?
Divide 63,360 (the inches in a mile) by the tire's circumference, which is its diameter times 3.1416. For a 35" tire: 63,360 / (35 x 3.1416) = 576 revolutions per mile. That is the number in the first chart below.
Why is the tire maker's number higher than the chart?
A tire carrying the weight of a truck flattens slightly where it meets the ground, so it rolls a little shorter than its unloaded height. Published figures are measured loaded, so they usually run 2-4% higher than the math. For speedometer calibration and gearing, use the manufacturer's figure when you have it.
Do I need to re-gear for bigger tires?
Bigger tires make your gears act taller, which costs acceleration and towing power and can make an automatic hunt between gears. A common goal is to get back within about 5% of the stock effective ratio. 33s on most trucks are fine on stock gears; 35s on a truck with 3.21-3.73 gears usually feel sluggish; 37s and up almost always call for a re-gear. The gearing table below shows the ratio that restores the stock feel.
How do I fix my speedometer after installing bigger tires?
Most newer trucks and Jeeps can be recalibrated with a plug-in programmer or by a dealer by entering the new tire size or its revolutions per mile. Until then, your speedometer reads low: on 35s instead of a stock 31.6" tire, an indicated 60 mph is about 66 mph.
Planning a bigger setup? Check what fits your truck in the tire fitment guide and the bolt pattern chart, or build a wheel & tire package: we mount and balance it free and ship it ready to bolt on.