How to Measure a 6-Lug Bolt Pattern

What a 6-lug PCD measurement tells you

PCD, or pitch circle diameter, is the diameter of the imaginary circle passing through the centers of all six lug holes. It is usually written as:

6 × PCD

For example, 6 × 139.7 mm means the wheel has six lug holes arranged on a 139.7 mm pitch circle. The number of lugs and the PCD must both match the vehicle’s hub.

PCD is only one part of wheel fitment. A correct PCD does not, by itself, confirm that a wheel will fit. You must also check the center bore, offset, backspacing, lug-hole seat, thread requirements, wheel width, load rating, and clearance.

Tools and preparation

You can measure a six-lug wheel with:

• A vernier or digital caliper
• A steel ruler or tape measure
• A straightedge, if needed
• A calculator
• A clean, well-lit work area

Remove dirt, corrosion, and loose paint from the lug holes before measuring. Ideally, measure the wheel off the vehicle and place it flat on a stable surface. Do not rely on a measurement taken across a tire sidewall or while the wheel is loosely mounted.

Inspect the wheel markings first. The rear of the spokes, inner barrel, or mounting pad may include markings such as wheel diameter and width, offset, center bore, or PCD. A marking such as 6Jx15, for example, describes wheel width and diameter, not the bolt pattern. Some wheels include the PCD; others do not, and markings can be difficult to read on used wheels. Treat a measurement as confirmation rather than assuming every marking is complete or accurate.

Step-by-step: measuring a six-lug bolt pattern

Method 1: Measure between opposite lug-hole centers

This is the most direct method.

1. Number the six lug holes from 1 through 6.
2. Identify a hole and the hole directly opposite it. On a regular six-lug pattern, the opposite hole is three positions away–for example, hole 1 and hole 4.
3. Find the center of each hole.
4. Measure in a straight line from the center of one hole to the center of the opposite hole.
5. Record the result in millimetres or inches.

For a six-lug wheel:

PCD = center-to-center distance between opposite holes

If the distance is approximately 139.7 mm, the pattern is commonly expressed as 6 × 139.7 mm. If measuring in inches, convert the result:

millimetres = inches × 25.4

A ruler can provide a useful initial result, but a caliper is preferable when the difference between possible patterns is small.

Method 2: Measure two adjacent hole centers and double the result

The six holes form a regular hexagon. The center-to-center distance between adjacent holes is half the PCD.

1. Measure from the center of one hole to the center of the hole immediately next to it.
2. Multiply that distance by two.

PCD = 2 × adjacent center-to-center distance

For example, an adjacent center-to-center measurement of approximately 69.85 mm produces a PCD of approximately 139.7 mm.

This method is useful when opposite holes are difficult to access, but accurately locating both hole centers is important.

Method 3: Use hole edges when the centers are difficult to locate

If the caliper cannot easily measure from center to center, measure across opposite holes along a line that passes through both hole centers.

For opposite holes:

• Inner edge to inner edge + hole diameter = PCD
• Outer edge to outer edge − hole diameter = PCD

For example, if the inner-edge distance is 126.0 mm and the lug-hole diameter is 13.7 mm:

126.0 + 13.7 = 139.7 mm

This method depends on measuring exactly across the centerline. If the caliper is angled or the measurement is taken away from the hole centers, the result will be inaccurate.

A caliper can also measure the hole diameter, but do not confuse the hole diameter with the lug thread size. The hole in a wheel is normally larger than the stud or bolt’s nominal thread diameter.

Verify the result rather than relying on one reading

Take at least two readings. For example:

• Measure between one pair of opposite holes.
• Measure between a different pair of opposite holes.
• If practical, measure an adjacent pair and double the result.

The results should agree closely. Significant variation can indicate that:

• The hole centers were estimated incorrectly.
• The caliper was not square to the wheel.
• Corrosion or damage is affecting the edge.
• The wheel has an unusual or damaged bolt pattern.
• The wheel is not a standard regular six-lug design.

If the wheel has elongated holes, visible repairs, cracks, or distortion around the mounting area, do not use the measurement alone to determine whether it is safe.

Common six-lug PCD measurement mistakes

Measuring the wrong hole pair

On a six-lug wheel, adjacent holes are not opposite holes. Opposite holes are separated by three hole positions. Measuring from hole 1 to hole 2 gives half the PCD when measured center to center, not the full PCD.

Measuring from edge to edge without correcting for hole diameter

An edge-to-edge distance is not automatically the PCD. You must add or subtract the lug-hole diameter according to the method used.

Measuring outside the hole centers

A measurement taken at an angle, or between points that are not aligned with the hole centers, can produce a misleading result. Use a straightedge or mark the estimated centers if necessary.

Rounding too early

Patterns that appear similar can still be different. Keep the full measured value until comparing it with a known specification. Do not treat 135 mm and 139.7 mm as interchangeable because both are “about 5.5 inches.”

Confusing PCD with other wheel dimensions

These dimensions are different:

A wheel may have the correct six-lug PCD but still fail to mount correctly because its center bore is too small, its offset causes interference, or its lug-seat design does not match the hardware.

How to interpret the result

Record the result in the same unit and format used by the wheel or vehicle specification. Common formats include:

• 6 × [millimetres]
• 6 × [inches]

Some specifications use an inch-based description that has a metric equivalent. For example, 5.5 inches converts to 139.7 mm. Do not assume that a rounded label is precise enough for every application; compare the measured value with the manufacturer’s stated specification.

If the measured PCD falls between two plausible patterns, repeat the measurement using the opposite-hole method and check any wheel markings. A bolt pattern gauge or a known, undamaged wheel with a verified specification can also help confirm the result. Do not force a wheel onto studs or bolts to test a questionable pattern.

What still requires physical fitment confirmation

After identifying the PCD, confirm all other relevant specifications before buying or installing the wheel:

1. Center bore: The wheel opening must clear the vehicle’s hub center. A larger bore may require an appropriate centering solution; a smaller bore generally prevents the wheel from mounting.
2. Offset and backspacing: These control the wheel’s position relative to the suspension, hub, bodywork, and fenders.
3. Lug-hole seat and hardware: Confirm whether the wheel uses conical, ball, or another seat type, and verify the required lug thread, nut or bolt style, and engagement.
4. Wheel width and diameter: Check clearance to brakes, suspension components, and bodywork.
5. Load rating and condition: This is especially important for used wheels. Inspect for cracks, bends, corrosion around the lug holes, repaired areas, and damaged sealing surfaces.
6. Tyre and vehicle clearance: Confirm that the intended tyre size and wheel assembly clear the brakes, steering components, suspension, and body through the full range of movement.

The correct result from a six-lug PCD measurement identifies the bolt-pattern requirement. It is the starting point for fitment, not a complete compatibility confirmation.