JK Wheel Backspacing & Offset Explained

Wheel offset and backspacing confuse more JK owners than almost any other spec. But understanding these measurements is crucial for proper fitment, handling, and avoiding expensive mistakes.

This guide explains what these numbers mean, what works for different JK builds, and how to choose the right specs for your setup.

Backspacing vs Offset: What’s the Difference?

Both measurements describe where the wheel mounting surface sits, just from different reference points.

Backspacing Explained

Backspacing measures the distance from the wheel’s mounting surface to the back edge of the wheel (the side facing the Jeep).

• More backspacing = wheel sits further inward toward the Jeep
• Less backspacing = wheel sits further outward (more “poke”)

Backspacing is measured in inches, typically ranging from 3.5” to 6” for JK applications.

Offset Explained

Offset measures the distance from the wheel’s centerline to the mounting surface.

• Positive offset = mounting surface is toward the outside of the wheel (wheel sits inward)
• Zero offset = mounting surface is at the wheel’s center
• Negative offset = mounting surface is toward the inside of the wheel (wheel sits outward)

Offset is measured in millimeters and can range from +50mm to -50mm for Jeep applications.

The Relationship Between Them

For the same wheel width, backspacing and offset directly correlate:

Wheel Width	Backspacing	Approximate Offset
9”	5.5”	+12mm
9”	5.0”	0mm
9”	4.5”	-12mm
9”	4.0”	-25mm
9”	3.5”	-38mm

Important: This relationship changes with wheel width. A 4.5” backspacing wheel that’s 8” wide has different offset than a 4.5” backspacing wheel that’s 9” wide.

Stock JK Wheel Specifications

Understanding what came from the factory helps you understand how aftermarket wheels differ.

Spec	Stock JK Value
Bolt Pattern	5x5 (5x127mm)
Wheel Size	17x7.5 or 18x7.5
Offset	+44mm to +50mm
Backspacing	~6”
Center Bore	71.5mm

The key takeaway: Stock JK wheels have very high positive offset, pushing the tires inward. This works fine with stock tire sizes but causes inner fender rubbing with larger tires.

Why Aftermarket Wheels Have Different Specs

When you install larger tires on stock wheels, the extra tire width extends inward toward the fender and suspension components. This causes rubbing at full steering lock or during suspension compression.

Aftermarket JK wheels solve this by using less backspacing (more negative offset), which pushes the entire wheel and tire assembly outward. This provides clearance for larger tires without fender rubbing.

The tradeoff: Pushing wheels outward affects steering geometry and puts more stress on front-end components. Finding the right balance is key.

Recommended Specs by Build Type

Stock Height JK

Running 33x10.50 or smaller tires

You can likely run stock wheels without issues. If you want an aggressive stance or are experiencing mild rubbing:

• Wheel size: 17x8 or 17x8.5
• Backspacing: 5.0-5.5”
• Offset: 0mm to +12mm

This minor change provides clearance while keeping wheels relatively close to stock position.

Stock to 2-Inch Lift with 33s

The most common mild build

• Wheel size: 17x9
• Backspacing: 4.5-5.0”
• Offset: -12mm to 0mm

This setup works great for 33x12.50 tires. The wheels will sit slightly outboard of the fenders for a mild “poke” that looks good and provides clearance.

2.5-Inch Lift with 35s

The JK sweet spot

• Wheel size: 17x9
• Backspacing: 4.5”
• Offset: -12mm

This is the most popular JK wheel spec for good reason. It provides excellent clearance for 35x12.50 tires while maintaining acceptable steering geometry. Our complete wheels and tires guide covers full fitment details.

3.5-Inch+ Lift with 37s

Serious builds

• Wheel size: 17x9
• Backspacing: 4.0-4.5”
• Offset: -25mm to -12mm

Larger tires sometimes require even less backspacing for fender clearance. However, going below 4” backspacing starts creating issues (covered below).

How Offset Affects Your JK

Changing from stock offset isn’t just about tire clearance. Here’s what else changes:

Steering Feel

Lower offset (wheels pushed outward) increases scrub radius - the distance between where the steering axis meets the ground and where the tire centerline meets the ground.

Effects of increased scrub radius:

• Steering wheel feedback increases
• Steering effort increases slightly
• Bumps and road imperfections transmit more feedback
• Steering can feel “wandery” at extreme offsets

Most JK owners find specs down to -12mm offset perfectly livable. Below -25mm, steering character changes noticeably.

Component Wear

Wheels pushed outward create a longer lever arm that puts more stress on:

• Wheel bearings
• Ball joints
• Tie rod ends
• Unit bearings

The real-world impact: With reasonable offset changes (-12mm to 0mm), component life isn’t significantly affected. Going to extreme negative offset (-38mm and beyond) measurably increases wear rates.

Track Width

Lower offset increases your JK’s track width (distance between left and right tires). This can:

• Improve stability in corners
• Look more aggressive
• Cause tires to extend beyond fenders (potentially illegal in some states)
• Throw more road debris on body panels

Wheel Width Considerations

Wheel width matters just as much as offset for proper fitment.

Matching Wheel Width to Tire Width

Tire Width	Recommended Wheel Width
10.50”	7.5-8.5”
11.50”	8-9”
12.50”	9-10”
13.50”	10-11”

Why this matters: A tire mounted on a wheel that’s too narrow will bulge excessively, causing sidewall stress and handling issues. A tire on a wheel that’s too wide will have an overly flat profile.

For most JK builds running 35x12.50 tires, a 17x9 wheel is ideal.

The 17 vs 18-Inch Debate

Most JK owners choose 17-inch wheels over 18-inch for these reasons:

• More sidewall: Extra cushion off-road, better protection against wheel damage
• Better tire selection: More off-road tires available in 17-inch sizes
• Lower cost: 17-inch tires are typically cheaper
• Easier to find: More common for emergency replacement

18-inch wheels work fine if you prefer the aesthetic, but there’s no performance advantage.

Popular Wheel and Offset Combinations

These combinations are proven to work well on JKs:

The Safe Choice

• Wheel: 17x9 with 4.5” backspacing (-12mm offset)
• Works with: 33-35” tires
• Lift requirement: 2”+ recommended for 35s

This is the most common JK wheel spec. Virtually every wheel manufacturer offers this configuration.

The Aggressive Stance

• Wheel: 17x9 with 4.0” backspacing (-25mm offset)
• Works with: 35-37” tires
• Lift requirement: 2.5”+ required

More tire poke, more aggressive look. Works well with lifted builds but increases component stress slightly.

The Mild Build

• Wheel: 17x8.5 with 4.75” backspacing (approximately 0mm offset)
• Works with: 33” tires
• Lift requirement: Stock to 2”

Keeps wheels closer to stock position while still providing clearance. Good for owners who want a clean look without excessive poke.

Wheel Spacers: A Word of Caution

Some owners use wheel spacers to push stock or incorrectly-spec’d wheels outward. While this works, consider:

Potential issues with spacers:

• Additional points of failure
• Must be retorqued regularly
• Can cause vibration if not properly fitted
• Lower quality spacers can crack or fail

If you use spacers:

• Only use hub-centric spacers
• Choose quality brands (Spidertrax, Synergy)
• Retorque after 100 miles and periodically thereafter
• Keep spacer thickness under 1.5”

Our recommendation: For significant offset changes, buying wheels with correct specs is safer and often not much more expensive than quality spacers.

Common Fitment Mistakes

Buying Wheels with Too Much Backspacing

Wheels with stock-like backspacing (5.5”+) push larger tires inward, causing inner fender rubbing. This is the most common mistake new JK owners make.

Ignoring Wheel Width

Mounting 12.50-inch wide tires on 7.5-inch wide wheels causes excessive tire bulge. Always match wheel width to tire width.

Going Too Aggressive on Offset

Extremely negative offset (-38mm and beyond) looks aggressive but:

• Accelerates component wear
• Changes steering feel dramatically
• May put tires beyond fenders (legal issues)
• Throws more debris on body panels

Forgetting About the Spare

Whatever wheel and tire combo you run, you need a matching spare. Budget for five wheels and five tires, not four.

Making Your Decision

For most JK owners, the decision is straightforward:

17x9 wheels with 4.5” backspacing (-12mm offset)

This spec:

• Fits 35x12.50 tires without issues
• Works with 33s if you’re running smaller
• Maintains acceptable steering geometry
• Available from virtually every manufacturer
• Proven on thousands of JKs

Only deviate from this if you have specific reasons:

• Running 37” tires (may need 4.0” backspacing)
• Want minimal poke (go to 5.0” backspacing)
• Running narrower tires (can use narrower wheels)

Related Articles

• Complete JK Wheels & Tires Guide - Full fitment information including tire sizing
• Best All-Terrain Tires for JK - Top A/T tire picks
• Best Mud-Terrain Tires for JK - Top M/T tire picks
• Best JK Lift Kits - Lift options that affect tire clearance
• JK Death Wobble: Causes and Fixes - Front end issues that can result from incorrect wheel specs

---

Frequently Asked Questions

What is the best wheel offset for a JK Wrangler?

For most JK builds, -12mm to 0mm offset (equivalent to 4.5-5.0 inch backspacing on a 9-inch wide wheel) provides the best balance. This pushes the tires outward enough for adequate fender clearance with larger tires while maintaining acceptable steering geometry and avoiding excessive stress on front-end components.

What is the stock JK wheel offset?

Stock JK wheels have approximately +44mm to +50mm offset with roughly 6 inches of backspacing on 7.5-inch wide wheels. This high positive offset positions the tires well inward, which works for stock tire sizes but causes rubbing issues when larger tires are installed.

Will wrong offset damage my JK?

Moderately negative offset (-12mm to -25mm) won’t cause significant issues and is appropriate for most JK builds. Extremely negative offset (below -38mm) puts additional stress on wheel bearings, ball joints, and tie rod ends due to the increased lever arm. It also dramatically changes scrub radius, affecting steering feel and potentially causing premature component wear.

Can I run spacers instead of new wheels?

Wheel spacers can work for minor adjustments (1-1.5 inches) when quality hub-centric spacers are properly installed and regularly retorqued. However, spacers add complexity and potential failure points to your setup. For significant offset changes, purchasing wheels with correct specifications is the safer and often more cost-effective long-term solution.

What backspacing do I need for 35-inch tires?

For 35-inch tires on a JK, 4.5-inch backspacing (-12mm offset) on a 17x9 wheel is the most common and widely recommended setup. This provides adequate inner fender clearance while keeping the tire position within acceptable limits for steering geometry and component longevity. With a 2.5-inch or greater lift, this combination fits without rubbing issues.