How long does it take to inflate a 275/65R18 tire?
A 275/65R18 tire (about 32.1 inches tall) holds roughly 83 liters. Raising it from 30 to 35 psi takes about 2 min 2 s with a compact 12V or cordless inflator, and filling it from flat to 35 psi about 14 min 12 s, or 5 min 14 s with a heavy-duty compressor.
VIAIR 85P/00085 Portable Tire Inflator, 12V Air Compressor for Cars & SUVs
A heavy-duty inflator suits a 83 liter tire: it moves enough air to fill one without overheating.
How long for each inflator class?
Times for one 275/65R18 tire using delivered flow at tire pressure, which is roughly 40 to 50 percent of the rated figure on the box: about 14, 22 and 38 liters per minute for the three classes.
| Job | Air to pump | Compact | Fast cordless | Heavy-duty |
|---|---|---|---|---|
| Top up 30 to 35 psi | 28 L | 2 min 2 s | 1 min 17 s | 45 s |
| Top up 25 to 35 psi | 57 L | 4 min 3 s | 2 min 35 s | 1 min 30 s |
| Low tire 15 to 35 psi | 114 L | 8 min 7 s | 5 min 10 s | 2 min 59 s |
| Flat 0 to 35 psi | 199 L | 14 min 12 s | 9 min 2 s | 5 min 14 s |
What do the numbers in 275/65R18 mean?
275 is the section width in millimeters. 65 is the sidewall height as a percentage of the width, here 179mm. R18 means radial construction on a 18 inch rim. Together they give an overall diameter of about 32.1 inches and an internal volume of about 83 liters, which puts it in pickup and large SUV territory where inflator size matters.
Check pressure cold, before driving. All four tires from 30 to 35 psi take about 8 min 7 s with a compact unit.
Inflators and a gauge for 275/65R18 tires
Prices change often.
Nearby tire sizes
Frequently asked questions
What is the air volume of a 275/65R18 tire?
About 83 liters, estimated from the sidewall size: 275mm wide, a 65 percent sidewall (179mm) and a 18 inch rim. To add 5 psi you pump in about 28 liters of free air, because each 14.7 psi of pressure equals one tire volume of outside air.
Can a small tire inflator fill a 275/65R18 tire?
Yes, but slowly: a flat 275/65R18 takes about 14 min 12 s with a compact unit, which is past the roughly 10 minute duty cycle many are rated for, so you may need a cool-down break. A heavy-duty 12V compressor does it in about 5 min 14 s without stopping. Always inflate to the door-jamb placard, not the sidewall maximum.
How much does a 275/65R18 tire lose in cold weather?
Like every tire, about 1 psi per 10 F drop. A 275/65R18 set to 35 psi at 70 F reads about 30 psi at 20 F. Put back the 27 liters of air it is missing when you check it on a cold morning.