Wheelfitment

How to Measure Bolt Patterns

How to Measure Wheel
BackSpace

Items required to measure wheel backspace:
Tape measure
Straight edge
Wheel w/o tire (preferred)

The easiest way to measure backspace is to lay the wheel face down onto
the ground so the backside of the wheel is facing up. Take a straight
edge and lay it diagonally across the inboard flange of the wheel. Take
a tape measure and measure the distance from where the straight edge
contacts the inboard flange to the hub mounting pad of the wheel. This
measurement is backspace. The above photo shows three wheels with
2",3", & 4" backspace.

Measuring Wheel Offset

To calculate offset you'll need the following measurements:

Wheel backspace
Wheel Width
Wheel Center line (outboard flange to inboard flange measurement / 2)

Subtract:
Wheel center line from Wheel backspace to get offset. If backspace is less than the wheel centerline the
offset is negative
If backspace is greater than the wheel centerline the offset is positive

Tip:
To convert from inches to mm multiply by 25.4
To convert from mm to inches divide by 25.4

Bolt pattern or lug pattern or bolt circle is determined by the number of bolt holes and the bolt
circle diameter.

Hub Diameter or center bore is the hole at the center of the wheel.

Rear spacing or back spacing is the distance from the backside of the wheel mounting pad to the
outside of the rim flange.

Offset: The distance from the centerline of the wheel to the mounting surface of the wheel.

Negative offset: When the back of the bolt pad is closer to the inside of the wheel; when
mounting surface is inboard of the rim centerline.

Positive offset: When the back of the bolt pad is closer to the street side of the wheel; when
the mounting surface is outboard of the rim centerline.

Bead-Loc A device which captures the tire bead between it's flanges, usually secured by bolts to
keep tire bead from dismounting. Usually used in dirt circle track or off road applications where
low tire pressures are used and hitting ruts or other vehicles are common. Left: An example of a
Bead-Loc wheel

Lug Size Ft                  Lbs Torque
7/16"                                    55-65
1/2"                                      75-85
9/16"                                   95-115
5/8"                                   135-145
14mm                                  85-95

IMPORTANT NOTICE:
As with all types of wheels retorque lug nuts after the first 25
miles & at 100 mile intervals until lug torque is maintained.
Note: Always refer to Owner's Manual for proper factory
specifications that take precedence over the listed
recommendations.

B ack to Wheels

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Sugar Land, Texas U.S.A
Bus: (832) 886-1677
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scott@scottmarlow.net
1 (866) 761-0974

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