Jeep Wheels - More Tech Tidbits

Bolt Pattern

The bolt pattern or bolt circle is the diameter of an imaginary circle formed by the centers of the wheel lugs. Bolt patterns can be 4, 5, 6, or 8 lug holes. A bolt circle of 4x100 would indicate a 4 lug pattern on a circle with a diameter of 100mm.

The diagram indicates the proper measuring methods. 6 lug wheels are measured like the 4 lug wheels.

Centerbore

The centerbore of a wheel is the size of the machined hole on the back of the wheel that centers the wheel properly on the hub of the car. This hole is machined to exactly match the hub so the wheels are precisely positioned, minimizing the chance of a vibration. With a hubcentric wheel, the lug hardware will not be supporting the weight of the vehicle, all they really do is press the wheel against the hub of the car. Some wheels use high quality, forged centering rings that lock into place in the back of the wheel. This is an acceptable alternative.

If you have non-hubcentric (lugcentric) wheels, they should be torqued correctly while the vehicle is still off of the ground so they center properly. The weight of the vehicle can push the wheel off-center slightly while you're tightening them down if left on the ground.

Offset

The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types.

Zero Offset
The hub mounting surface is even with the centerline of the wheel.

Positive
The hub mounting surface is toward the front or wheel side of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.

Negative
The hub mounting surface is toward the back or brake side of the wheels centerline. "Deep dish" wheels are typically a negative offset.

If the offset of the wheel is not correct for the car, the handling can be adversely affected. When the width of the wheel changes, the offset also changes numerically. If the offset were to stay the same while you added width, the additional width would be split evenly between the inside and outside. For most vehicles, this won't work correctly.

Proper Lug Nuts

While many aftermarket alloy wheels are designed to use your car’s original lug nuts or bolts, others require new hardware. It may be something as critical as differences in the wheel’s lug seat design as shown below, or something as simple as shorter lug heads to allow the wheel’s center caps to fit. Keep a set of your vehicle’s original lug nuts or bolts in the trunk just in case you ever need to use your spare tire or borrow a spare on a stock rim.

Wheel Lug Nut Torquing

Proper installation requires that the wheel lug torque be set to the recommended specification for your vehicle. These torque specifications can be found in your vehicle’s shop manual or obtained from your vehicle dealer. Finish tightening the lugs down with an accurate torque wrench. Use a crisscross sequence (shown below) until they have reached their proper torque value. Be careful because if you over torque a wheel, you can strip a lug nut, stretch or break a wheel stud, and cause the wheel, brake rotor and/or brake drum to distort.

NOTE: When installing new wheels you should re-torque them after traveling the first 50 to 100 miles. This is necessary because as the wheels are “breaking in” they may compress slightly allowing their lugs to lose some of their torque. Simply repeat the same torque procedure listed above.