Car Care Forum | Black's Tire and Auto Service

BTS on Custom Wheel Fitments

Fri, 06 Feb 2009 21:37:55 +0000

Some wheels may also require “HUB CENTRIC RINGS” which match the wheel to the vehicle’s hub for a true “centered” installation.

Many aftermarket wheels may need these rings to prevent off-centering during installation that can cause vibration.

BTS on Custom Wheel Fitments

Fri, 06 Feb 2009 21:37:41 +0000

Proper Fitment information - here is a glossary of useful terms to help determine what wheel combinations will work or not.

*BACK SPACING: The distance from the backside of the wheel mounting pad to outside of the rim flange.
*HUB DIAMETER: (or center bore) The hole at the center of the wheel & used to center the wheel.
*BOLT PATTERN: (or lug nut pattern) Spacing or distance b/t lug studs.
*OFFSET: The distance from the centerline of the wheel to the mounting surface.
*POSITIVE OFFSET: When the back of the bolt pad is closer to the street side of the wheel; when mounting surface is outboard of the rim centerline.
*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.

When determining that selected wheel meets the requirements of a particular vehicle, make sure it is compatible with the mechanical aspects, such as suspension clearance. Tie rod ends, A-arms, brake calipers, shocks & mounts may be potential trouble spots. Another area of concern is both the inside and outside fender clearance. This should be checked by turning steering wheel lock to lock from left to right with suspension fully collapsed.

BTS on Custom Wheel Fitments

Fri, 06 Feb 2009 21:37:22 +0000

Bolt pattern: (or lug nut pattern) is determined by the number of lug studs and the spacing between them.
Different vehicles and wheel manufacturers use two methods to measure bolt patterns - standard & metric.
Listed here are common bolt patterns paired with their equivalent conversions from standard to metric.

4×4.25 = 4×108
4×4.50 = 4×4.5

5×4.25 = 5×108
5×4.50 = 5×4.5
5×4.75 = 5×120.7
5×5.00 = 5×127
5×5.50 = 5×139.7

6×4.50 = 6×114.3
6×5.00 = 6×127
6×5.50 = 6×139.7

8×6.50 = 6×165.1

FORMULA for Standard to Metric Conversion =
1 inch + 25.4

To convert inches to millimeters: multiply by 25.4
example: 4.75 x 25. = 120.65
To convert millimeters to inches: divide by 25.4
example: 100 mm divided by 25.4 = 3.937″