tireheight.com315/70R18 in inches
A 315/70R18 tire is 35.4″ tall and 12.4″ wide, and fits a 18″ wheel. In inches it is written 35.4×12.4R18.
How tall 315/70R18 tires really are
Heights published by Toyo for the one tire in this size. Their published revolutions per mile work out to 34.7″ under load (below).
The one tire listed, the Toyo Open Country M/T, measures 35.71″: 0.35″ taller than the size code's 35.36″.
Published revs per mile (581) mean the tire rolls like a 34.7″ tire on the vehicle. Use this for speedometer calibration.
1 tire in 315/70R18
Sort by the spec you care about.
Is 315/70R18 a 36-inch tire?
Yes. The size code works out to 35.36″, and the 1 tire here publishes 35.71″, so people call it a 36.
All 36-inch tire sizes, on every wheel size.
Compare with nearby sizes
Differences in overall diameter, calculated from each size code.
| Size | Diameter ″ | vs 315/70R18 | Difference |
|---|---|---|---|
| 295/70R18 | 34.26 | -1.10″ | -3.1% |
| 325/65R18 | 34.63 | -0.73″ | -2.1% |
| 305/70R18 | 34.81 | -0.55″ | -1.6% |
| 285/75R18 | 34.83 | -0.53″ | -1.5% |
| 35×12.50R18 | 35.00 | -0.36″ | -1.0% |
| 35×10.50R17 | 35.00 | -0.36″ | -1.0% |
| 35×11.50R17 | 35.00 | -0.36″ | -1.0% |
| 35×12.50R17 | 35.00 | -0.36″ | -1.0% |
| 37×12.50R18 | 37.00 | +1.64″ | +4.6% |
| 37×13.50R18 | 37.00 | +1.64″ | +4.6% |
How to read 315/70R18
Marks a light truck (LT) tire.
A percentage, not a measurement: the sidewall is 70% as tall as the tire is wide, which is 220.5 mm or 8.68 inches.
Radial construction.
Mounts on a 18-inch wheel. Approved wheel widths run 8.0″ to 11.0″.
Each tire carries up to 3,860 lb (1,750 kg) on its own, or 3,525 lb (1,600 kg) each when paired on a dual rear axle.
Rated for up to 99 mph sustained.
Printed separately as "LOAD RANGE E": a 10-ply rating, inflated up to 80 psi (standard load-range table). The load range E tires here carry up to 3,860 lb each, as published.
| Specification | Inches | Metric |
|---|---|---|
| Overall diameter | 35.36 | 898 mm |
| Section width | 12.40 | 315 mm |
| Sidewall height | 8.68 | 220.5 mm |
| Circumference | 111.1 | 2,822 mm |
| Revolutions per mile (calculated, unloaded) | 570.3 | 354 per km |
| Revolutions per mile (published by manufacturers) | 581 | 361 per km |
| Approved wheel width | 8.0–11.0 | 203–279 mm |
Speedometer error after switching to 315/70R18
Questions about 315/70R18
What is 315/70R18 in inches?
35.36 inches tall, 12.40 inches wide, on a 18-inch wheel. Written in inches, that is roughly 35.4×12.4R18.
What wheel width do I need for 315/70R18?
Manufacturers approve 8.0–11.0″ wide wheels for this size.
How many revolutions per mile does a 315/70R18 make?
Published figures run 581 revolutions per mile. The calculated figure is 570.3, but manufacturers measure the tire under load, where it rolls on a smaller radius.
How much taller is 315/70R18 than 35×12.50R18?
0.36 inches taller on paper (35.36″ vs 35.00″), which raises the axle about 0.18″. Your speedometer will read about 1.0% slow.