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420/85R34 tire size

Tractor drive tire.

What 420/85R34 means

420 mm nominal section width, 85 aspect ratio, R radial, for a 34-inch rim.

Dimensions

Rolling circumference
187.0 in (4,750 mm)
RCI group
43 (about 63 in tall, rolling circumference ≈ 187 in)

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

Equivalent sizes

Same height and width, same 34" rim: 16.9R34.

480 mm (18.4")
480/70R34
520 mm (20.8")
540/65R34

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

Full conversion →

Sources: Continental Agricultural Tires Technical Databook, Firestone Ag RCI chart, Firestone hydroinflation tables. Checked October 2026. How we source data.

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