spacing - The measurement from the mounting pad to the inner edge of the
Bead seat - The position
where the tire rests and seals on the inside of the rim.
Bolt Circle - The
diameter of an imaginary circle drawn through the center of each lug hole. Also
referred to as the bolt pattern.
Center Bore - The
hole in the center of the wheel machined to match the hub of specified vehicles
with hub-centric wheels and machined to a generic size with lug centric wheels.
Hub centric - The
center bore hole of a wheel matches the hub diameter of the vehicle. This centers
the wheel via the center hole rather than the lug nuts.
Hub centric ring(s)
- A nylon insert for the center bore of the wheel that keeps the wheel concentric
to the vehicle's hub during installation.
Load rating - The
maximum weight that the wheel is designed to support. To determine load rating
requirements take the gross axle weight ration and divide by 2.
Lug centric - When
the wheel is centered by the bolt holes/ lug nuts of the wheel, rather than
by the center bore. Lug centric wheels should be balanced from the bolt holes.
Make - The brand
name of the vehicle. For example, Ford, Chevrolet, Honda.
Model - The particular
style name of the vehicle. For example, F-150, Corvette, Civic.
Mounting pad - The
surface area on the back of the wheel's center that contacts the brake drum
or rotor surface.
MSRP - This is the
manufacturer suggested retail price per wheel. The dealer sets actual retail
Negative offset -
When the mounting surface is closer to the disk/drum (Inside) of the wheel.
Or the mounting pad is behind the centerline of the wheel. This type of wheel
is commonly referred to as a deep-dish wheel. This offset is common in older
vehicles and many of today's trucks and will bring the wheel/tire combination
out away from the vehicle.
Offset - The offset
of the wheel is the distance from the mounting pad to the centerline of the
Positive offset -
The mounting pad is forward of the centerline of the wheel, towards the street
side of the wheel. This is common in most front wheel drive cars and some newer
trucks. Generally speaking a positive offset wheel brings the wheels closer
to the center of the vehicle.
Plus 1/ plus 2 sizing
- A concept to improve handling and performance through the mounting of lower
profile tires to wheels that are 1, 2 or even 3' greater in diameter. The overall
ride height remains the same.
Rim width - The width
of the custom wheel, measured from bead seat to bead seat not edge to edge.
Rim Diameter - The
overall diameter of the wheel's bead seat, not the diameter of the rim edge.
Rim flange - The
outermost edge of the wheel's rim that the clip-on weights attach to on most
Safety bead - The
raised area circling the rim of the wheel and located slightly inward from the
Spring clips - Push
on retainer clips that hold the brake from on the disc rotor to the axle during
Star pattern - The
proper way for sequential torquing of the lugs in a 5 lug bolt circle.
Torquing - The securing
of the wheel/tire assembly to the automobile by the tightening of the wheel's
lug nuts to the studs of the vehicle's hub. Custom wheels should always be torqued
with a manual torque wrench (not an impact air wrench) to torque rating specifications
followed by periodic re-torquing.
Torque rating - The
proper pressure to be applied in foot pounds when tightening lug nuts to secure
the wheel/tire assembly to the automobile.
Unsprung weight -
The total weight of the vehicle not supported by the suspension system. For
example wheels and tires.
Wheel weights - Weights
that are used to balance the wheel/tire assembly. They are either clipped, taped,
or self adhered to the inside or outside of the wheel.
Zero offset - The
distance from the mounting pad to the centerline of the wheel is 0