Track Size Explained: What 320x86x49 Means
A track size like 320x86x49 breaks down into three separate specs: 320mm width, 86mm pitch, and 49 links. Each number describes a different dimension of the track, and a track has to match all three to fit a given machine — not just the width.
The first number: width
320 is the track's width in millimeters, measured across the outer rubber tread. Width is the number most people already understand, since it's the visible dimension — a wider track spreads the machine's weight over more ground contact area, which lowers ground pressure. Common widths run from around 180mm on compact mini excavators up to 450mm or more on larger machines, in standard steps (180, 230, 260, 300, 320, 350, 400mm are typical).
The second number: pitch
86 is the pitch in millimeters — the center-to-center distance between two adjacent drive lugs on the inside of the track. Pitch is not a visible or intuitive spec, but it's the most critical one to get right, because pitch has to match the tooth spacing on the machine's drive sprocket exactly. If pitch is off, even by a small amount, the track won't engage the sprocket teeth evenly. That mismatch shows up as popping, jumping, uneven wear on the lugs, or the track walking off the undercarriage entirely.
The third number: link count
49 is the link count — the total number of drive lugs around the full loop of the track. This number determines the track's overall length and how it wraps around the sprocket, idlers, and rollers. Two tracks can share the same width and pitch but need a different link count if they're built for undercarriages of different overall length.
Why all three numbers have to match
Width alone tells you almost nothing about fit. A track can be the exact width you need and still be wrong for the machine if the pitch doesn't match the sprocket or the link count doesn't match the undercarriage length. Manufacturers and suppliers list track sizes in the same width-pitch-link order specifically so all three can be checked against a machine or an old track at once.
How this differs from tire sizing
Tire sizing (like a skid steer's 10x16.5 designation) describes section width and rim diameter — two numbers, no pitch or link count, because a tire doesn't need to mesh with sprocket teeth the way a track does. Rubber tracks are a closed loop that has to index precisely onto a toothed drive wheel, which is why the sizing convention carries a third dimension tires don't need.
Where the numbers come from
Track manufacturers stamp or mold the size designation into the sidewall rubber of most production tracks, generally near the tread pattern. If that marking has worn away or was never legible, the size can also be found on the machine's parts manual, cross-referenced by serial number through the OEM, or measured directly off the old track and undercarriage — see the companion guide on how to measure rubber tracks for the measurement procedure.
Getting it wrong
A track ordered on width alone, without checking pitch and link count, is the single most common track-fitment mistake. Before ordering a replacement, confirm all three numbers against either the existing track's sidewall marking or your machine's OEM part number — never against the model name alone, since undercarriage variants mean the same machine model can take more than one track size.