20.8R38 tire size

What 20.8R38 means

20.8-inch nominal section width, R radial, for a 38-inch rim. The bias-ply version is written 20.8-38. This is the older inch system; the metric equivalent is listed below.

Rolling circumference

219.0 in (5,563 mm)

RCI group

46 (about 73 in tall, rolling circumference ≈ 219 in)

Continental Agricultural Tires Technical Databook (measured values) and the Firestone Rolling Circumference Index chart.

Same height and width, same 38" rim: 520/85R38.

600 mm (24.5")

650/65R38

Same height, other width — keeps front axle lead/lag about the same; needs the right rim width.

Full conversion →

Water, per tire

151.5 gal (573 L) = 1,263 lb (573 kg)

CaCl₂ 3½ lb/gal, per tire

1,538 lb (698 kg) total

CaCl₂ 5 lb/gal, per tire

1,635 lb (742 kg) total

Firestone hydroinflation tables, 18.0" rim. Other rims and tire counts →

• Tractor tire size conversion
• Lead/lag calculator
• Liquid ballast chart
• Axle load with implements