Taking Measurements
Accurate measurements are essential to finding the right wheel for your application. Here’s how we take the most common wheel measurements.
1. How do I measure backspace?
Place the wheel (without tire) on a flat surface, face UP.
Put a ruler down through the center hub hole.
The distance from the flat surface to the bottom side of the center is the wheel backspacing.
2. What is offset?
Offset and backspacing are two terms commonly used in wheel measurement that can be
confusing at times. Advertised wheel width is generally measured at the inside tire bead mounting
surface, but you must determine the overall wheel width from the front to rear lip – usually 1-inch
total. So a wheel that is advertised as 15×8 is 15-inches in diameter, 8-inches from tire bead to
tire bead but 9-inches wide overall.
Offset is the distance from the mounting pad to the centerline of the wheel. Offset can be positive
(more backspacing) or negative (less backspacing).
Backspacing is the measurement from the mounting pad to the inner edge of the wheel.
To order Circle Racing Wheels, you’ll need to measure backspacing, not offset.
3. How do I determine my bolt pattern?
Wheel Care
Great wheels deserve great care; here are some tips to help you get the most from your Circle wheels.
| 1. Do I need to do anything to my new Circle Racing Wheels before I can use them? |
 |
ALWAYS remove the powdercoat from the coined lug seat area prior to using the wheel for the first time. Powdercoat between the lug nut and wheel will cause the lug nut to loosen. CRW recommends this type of pilot brush: |
2. Can I use lug nuts from a street car?
With our steel wheels, CRW recommends using the highest quality steel racing lug nuts only.
Lug nuts should be hardened and have a 45 degree taper on 5/8 lug or a 60 degree on a 1/2 lug.
3. Is there anything special I should know about mounting my race wheel on the car?
All Circle Racing Wheels are lug centered. Make sure all lug nuts are in place and seated into
the coined lug seat area to properly center your wheel before torquing. Tightening one lug nut
before installing all five could mount the wheel off-center and damage your wheel.
4. What do I use to clean my wheels?
CRW recommends using soapy water and a soft cloth. Do not use brake cleaner, carburetor
cleaner, etching-type wheel cleaners, or any harsh chemicals. Using these chemicals will
cause damage to the finish.