Basic Wheel Terms

by **JazzGD1** Wed 30 Mar 2011, 8:23 am

OFFSET
The offset of a wheel is the measurement of the hub surface contact area in offset from the center line of the overall rim width of the wheel. A wheel whose hub surface contact area sits further towards the outside of the wheel than the center line has a positive offset. A wheel whose hub surface contact area sits further towards the inside of the wheel than the centerline has a negative offset

To determine the offset, the wheel must be measured accurately using the following steps:
(1) measure the overall rim width of the wheel.
(2) measure the T dimension (Backspace), which is the measurement from the hub surface contact area to the outside of the inner rim.
(3) divide the overall rim width by 2 which gives you the center line.
(4) subtract the center line (overall rim width/2) from the T dimension (Backspace).
(5) a negative answer means the wheel has a negative offset and a positive answer means the wheel has a positive offset

PCD
The Pitch Circle Diameter is the diameter of the circumference of the center line of the lug nut holes, this can be four, five or six lug. The easiest way of measuring four or six lug wheels is take the diagonal holes and measure from the outer edge of one hole to the inner edge of the second hole. With five lug wheels this is not possible as there are not diagonal holes, therefore the simplified way would be to measure the outer circumference and inner circumference of the holes. The difference should be divided by two and added onto the smaller circumference or deducted from the larger circumference.

CENTER BORE
The center bore is the location hole machined in the center of the wheel and this varies from one vehicle to another. It is essential the wheels purchased have the correct center bore for the vehicle they are to suit, otherwise you may experience balancing problems.

CALIPER CLEARANCE
Some vehicles as standard are produced using large brake calipers, therefore our listings have taken this into account when advising fitments. You should advise your wheel supplier if you have modified the brakes on your vehicle.

Basic Wheel Terms BasicWheelTerms

by nickf601 Wed 30 Mar 2011, 10:51 am

lesson time .......

by **sevenseaters** Wed 30 Mar 2011, 11:05 am

bro FreedGB3, thanks for the lessons, but frankly speaking, i stracth my head when reading this scratch

Is there any easier way to understand and differenciate which one should be followed Negative Offset or Positive Offset?

(5) a negative answer means the wheel has a negative offset and a positive answer means the wheel has a positive offset

please enlighten us Shocked