tireheight.com40×13.50R18 in inches
A 40×13.50R18 tire is 40.0″ tall and 13.5″ wide, and fits a 18″ wheel.
How tall 40×13.50R18 tires really are
Heights published by BFGoodrich for all 2 tires in this size. Their published revolutions per mile work out to 38.3″ under load (below).
Real 40×13.50R18 tires measure 39.50″, against 40.00″ from the size code. Every one runs shorter than the size code.
- BFGoodrich All-Terrain T/A KO339.50″ −0.50″
- BFGoodrich HD-Terrain T/A KT39.50″ −0.50″
Published revs per mile (526) mean the tire rolls like a 38.3″ tire on the vehicle. Use this for speedometer calibration.
The lightest (BFGoodrich All-Terrain T/A KO3, LT F) is 7.4 lb lighter per corner than the heaviest (BFGoodrich HD-Terrain T/A KT, LT F).
2 tires in 40×13.50R18
Sort by the spec you care about.
Is a 40×13.50R18 really 40 inches tall?
Shorter. The name says 40″, and the 2 tires here publish 39.50″.
All 40-inch tire sizes, on every wheel size.
Compare with nearby sizes
Differences in overall diameter, calculated from each size code.
| Size | Diameter ″ | vs 40×13.50R18 | Difference |
|---|---|---|---|
| 38×11.50R18 | 38.00 | -2.00″ | -5.0% |
| 38×13.50R18 | 38.00 | -2.00″ | -5.0% |
| 38×15.50R18 | 38.00 | -2.00″ | -5.0% |
| 38×11.50R17 | 38.00 | -2.00″ | -5.0% |
| 38×12.50R17 | 38.00 | -2.00″ | -5.0% |
| 39×13.50R17 | 39.00 | -1.00″ | -2.5% |
| 40×12.50R17 | 40.00 | 0.00″ | 0.0% |
| 40×13.50R17 | 40.00 | 0.00″ | 0.0% |
| 42×13.50R17 | 42.00 | +2.00″ | +5.0% |
| 42×14.50R17 | 42.00 | +2.00″ | +5.0% |
How to read 40×13.50R18
40 inches tall, measured on the approved wheel. Flotation sizes give every number in inches.
13.50 inches across the widest point, or 343 mm.
Radial construction.
Mounts on a 18-inch wheel. Approved wheel widths run 9.0″ to 11.5″.
Marks a light truck (LT) tire.
Each tire carries up to 3,970 lb (1,800 kg) at its maximum pressure.
Rated for up to 106 mph sustained.
Printed separately as "LOAD RANGE F": a 12-ply rating, inflated up to 95 psi (standard load-range table). The load range F tires here carry up to 3,970 lb each, as published.
| Specification | Inches | Metric |
|---|---|---|
| Overall diameter | 40.00 | 1016 mm |
| Section width | 13.50 | 343 mm |
| Sidewall height | 11.00 | 279.4 mm |
| Circumference | 125.7 | 3,192 mm |
| Revolutions per mile (calculated, unloaded) | 504.2 | 313 per km |
| Revolutions per mile (published by manufacturers) | 526 | 327 per km |
| Approved wheel width | 9.0–11.5 | 229–292 mm |
Speedometer error after switching to 40×13.50R18
Questions about 40×13.50R18
What is 40×13.50R18 in inches?
40.00 inches tall, 13.50 inches wide, on a 18-inch wheel. Manufacturers publish 39.50 inches for the 2 tires listed here.
How much does a 40×13.50R18 tire weigh?
Between 82.4 lb and 89.8 lb for the 2 tires listed here. The lightest is the BFGoodrich All-Terrain T/A KO3 (LT F); the heaviest is the BFGoodrich HD-Terrain T/A KT (LT F).
What wheel width do I need for 40×13.50R18?
Manufacturers approve 9.0–11.5″ wide wheels for this size.
How many revolutions per mile does a 40×13.50R18 make?
Published figures run 526 revolutions per mile. The calculated figure is 504.2, but manufacturers measure the tire under load, where it rolls on a smaller radius.
How much taller is 40×13.50R18 than 38×15.50R18?
2.00 inches taller on paper (40.00″ vs 38.00″), which raises the axle about 1.00″. Your speedometer will read about 5.3% slow.