Bolt Pattern For 1999 Jeep Grand Cherokee

Understanding the bolt pattern of your 1999 Jeep Grand Cherokee is crucial for several reasons, whether you're looking to upgrade your wheels, replace a damaged rim, or simply understand the technical specifications of your vehicle. The bolt pattern, sometimes referred to as the lug pattern, dictates which wheels will physically fit on your Jeep's hubs. Getting it wrong can lead to serious safety issues and incompatibility problems. This article will break down the bolt pattern for the 1999 Jeep Grand Cherokee in a way that's easy to understand, even if you're not a seasoned mechanic.

What is a Bolt Pattern?

At its core, a bolt pattern describes the arrangement of the lug holes on a wheel. It's defined by two key numbers: the number of lugs and the diameter of the circle that passes through the center of each lug hole. Think of it like this: imagine drawing a perfect circle that touches the center of each lug hole on your wheel. The diameter of that circle, combined with the number of lugs, gives you the bolt pattern.

For example, a bolt pattern of 5x114.3 (or 5x4.5 in imperial units) means the wheel has 5 lug holes and the diameter of the imaginary circle is 114.3 millimeters (or 4.5 inches). This is a very common bolt pattern, found on many Japanese and American vehicles, including some Ford Mustangs, Honda Accords, and Toyota Camrys.

The Bolt Pattern of the 1999 Jeep Grand Cherokee

The 1999 Jeep Grand Cherokee (WJ generation) has a bolt pattern of 5x139.7 mm (or 5x5.5 inches). This means it has 5 lug holes, and the diameter of the circle passing through the center of those holes is 139.7 millimeters (or 5.5 inches). This is a fairly common bolt pattern among Jeeps and some other SUV brands.

It's important to note that while other Jeep models might have different bolt patterns, the 1999 Grand Cherokee specifically uses 5x139.7mm. For instance, the Jeep Wrangler (TJ generation) also often uses the 5x114.3 (5x4.5) bolt pattern, which is different from the Grand Cherokee. Similarly, some later generation Grand Cherokees might have shifted to different bolt patterns, so always double-check based on the specific year and model.

Why is it Important to Know Your Bolt Pattern?

Knowing your bolt pattern is critical when:

Replacing Wheels: If you're replacing your wheels due to damage or upgrading to a different style, you need to ensure the new wheels have the correct bolt pattern. Installing wheels with the wrong bolt pattern is dangerous and simply won't work. The lug nuts won't align properly, and you won't be able to securely attach the wheel to the hub.
Installing Wheel Spacers/Adapters: Wheel spacers are used to push your wheels further out, improving the stance and sometimes allowing for larger tires. Adapters are used when you want to install wheels with a different bolt pattern. However, using adapters introduces complexity and potential points of failure, so they should be used with caution and only when necessary. If you are using spacers, ensure that they are hub-centric and properly sized for your 5x139.7mm hub.
Preventing Damage: Attempting to force a wheel with the wrong bolt pattern onto your vehicle can damage the wheel studs, hubs, and even the wheels themselves. This can lead to costly repairs and, more importantly, compromise your safety.
Ensuring Proper Fitment: Correct fitment includes more than just the bolt pattern. You also need to consider the wheel's offset, backspacing, and center bore. However, the bolt pattern is the fundamental requirement.

Understanding Offset and Backspacing (Briefly)

While the bolt pattern is the primary factor, offset and backspacing are equally important for proper wheel fitment. Offset refers to the distance between the wheel's mounting surface and its centerline. Backspacing is the distance from the wheel's mounting surface to its innermost edge.

A wheel with the wrong offset or backspacing can rub against the suspension components, fenders, or brake calipers. Always research the recommended offset and backspacing for your 1999 Jeep Grand Cherokee when selecting new wheels.

How to Find Your Bolt Pattern

There are several ways to determine the bolt pattern of your 1999 Jeep Grand Cherokee:

Check Your Owner's Manual: The owner's manual often contains information about the vehicle's wheel specifications, including the bolt pattern.
Look at the Wheel Itself: Sometimes, the bolt pattern is stamped on the inside of the wheel. You may need to remove the wheel to see it.
Online Resources: Many websites and online databases specialize in wheel and tire information. You can enter your vehicle's year, make, and model to find the correct bolt pattern.
Measure It Yourself (Carefully!): This is possible, but it requires precision and careful measurement. For a 5-lug pattern like the one on the Grand Cherokee, you'll need to measure the distance from the center of one lug hole to the outer edge of the lug hole directly opposite it. Due to the complexity of accurate measurement, it is better to refer to online databases or stamped on the wheel.
Consult a Tire/Wheel Professional: The easiest and most reliable method is to consult with a tire or wheel professional. They have the expertise and tools to accurately determine your vehicle's bolt pattern.

Tools and Considerations for Wheel Changes

If you're planning to change your wheels yourself, here are some essential tools and considerations:

Lug Wrench: A properly sized lug wrench is essential for loosening and tightening lug nuts.
Torque Wrench: Always use a torque wrench to tighten lug nuts to the manufacturer's specified torque. Over-tightening can damage the studs, while under-tightening can cause the wheel to come loose. The recommended torque specification for the 1999 Jeep Grand Cherokee is typically found in the owner's manual or a reliable repair manual.
Jack and Jack Stands: Use a jack to lift the vehicle and securely support it with jack stands before removing any wheels. Never work under a vehicle supported only by a jack.
Wheel Chocks: Place wheel chocks behind the wheels that are staying on the ground to prevent the vehicle from rolling.
Gloves: Protect your hands with gloves.
Safety Glasses: Wear safety glasses to protect your eyes from debris.

Practical Takeaways

Here's what you should remember about the bolt pattern for your 1999 Jeep Grand Cherokee:

The bolt pattern is 5x139.7mm (or 5x5.5 inches).
Knowing your bolt pattern is essential for replacing wheels, installing spacers/adapters, and preventing damage.
Always double-check the bolt pattern before purchasing new wheels.
Consider offset and backspacing for proper fitment.
Use a torque wrench to tighten lug nuts to the correct specification.
If in doubt, consult with a tire or wheel professional.

By understanding the bolt pattern and taking the necessary precautions, you can ensure a safe and successful wheel installation or replacement on your 1999 Jeep Grand Cherokee.