JK Wheels & Tires Guide: Fitment & Sizing

Q: What wheel backspacing do I need?

For JKs, 4.5 inch backspacing (or about -12mm offset) is the sweet spot for most tire sizes. This pushes the tires out slightly for better clearance while maintaining acceptable steering geometry.

Q: Are 35 inch tires worth it?

35s offer noticeably better off-road capability with more ground clearance and approach angles. However, they require at least a 2.5 inch lift, possible regearing, and impact fuel economy by 1-2 mpg. For serious off-roading, yes. For mostly pavement, 33s are often the better choice.

Wheels and tires are the most visible modification on any Jeep JK - and one of the most confusing to get right. Between tire sizing formats, wheel offset vs. backspacing, and fitment at different lift heights, there’s a lot to understand before you spend your money.

This guide covers everything you need to know to make the right choice for your build.

Understanding Tire Sizing: What the Numbers Actually Mean

You’ll see JK tires listed in two formats. Let’s decode both.

The “Inch” Format: 35x12.50R17

Number	What It Means
35	Overall tire diameter in inches
12.50	Tire width in inches
R	Radial construction
17	Wheel diameter in inches

So 35x12.50R17 = a 35-inch tall tire that’s 12.5 inches wide, designed for a 17-inch wheel.

The Metric Format: 285/70R17

Number	What It Means
285	Tire width in millimeters
70	Aspect ratio (sidewall height = 70% of width)
R	Radial construction
17	Wheel diameter in inches

To find the height: 285mm x 0.70 = 199.5mm sidewall. Two sidewalls (top and bottom) plus the 17” wheel = approximately 33 inches.

Common Size Conversions

Inch Size	Metric Equivalent	Actual Diameter
31”	265/70R17	31.6”
33”	285/70R17	32.7”
35”	315/70R17	34.4”
35”	35x12.50R17	34.5”
37”	37x12.50R17	36.8”

Important: Tires rarely measure their stated size exactly. A “35-inch” tire might actually measure 34.5 inches. Check the manufacturer’s specs.

Wheel Specifications Explained

Getting the right wheel isn’t just about diameter. Three specs matter for JK fitment.

Bolt Pattern

JK bolt pattern is 5x5 (or 5x127mm). This is different from the older TJ (5x4.5), so TJ wheels won’t fit your JK without adapters.

Backspacing

Backspacing is measured from the wheel’s mounting surface to the back edge of the wheel (the side that faces the Jeep).

More backspacing = wheel sits further inward
Less backspacing = wheel sits further outward (more “poke”)

Stock JK wheels have about 6” backspacing. Most aftermarket JK wheels run 4.5” backspacing.

Offset

Offset measures the same thing as backspacing, just differently. It’s the distance (in mm) from the wheel centerline to the mounting surface.

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

Stock JK offset is about +44mm. Most aftermarket wheels are -12mm to +12mm.

Backspacing vs. Offset: Quick Reference

For a 17x9” wheel (most common JK size):

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

The JK sweet spot: 4.5” backspacing (-12mm offset) on a 17x9 wheel. This provides good tire clearance without putting excessive stress on wheel bearings or dramatically changing your scrub radius.

What Fits at Each Lift Level

Here’s the practical guide to what actually fits without constant rubbing.

Stock Height

Tire Size	Fits?	Notes
31” (265/70R17)	Yes	Factory option on some models
32” (275/70R17)	Yes	No issues
33x10.50	Yes	Fits with stock wheels
33x12.50	Mostly	May need to trim fender liner, remove air dam
35”	No	Will rub significantly at full lock

2” Lift

Tire Size	Fits?	Notes
33x10.50	Yes	No rubbing
33x12.50	Yes	Minor trimming may help
35x12.50	Tight	Rubs at full lock, needs trimming

2.5” Lift

Tire Size	Fits?	Notes
33”	Yes	No issues at all
35x12.50	Yes	Some trimming recommended
37”	No	Will rub without significant mods

3.5”+ Lift

Tire Size	Fits?	Notes
35”	Yes	Fits well
37x12.50	Possible	Needs fender trimming or high-line fenders
37x13.50	Tight	May need flat fenders

Rubicon owners: Your fenders sit about half an inch higher than Sport/Sahara models. This gives you slightly more clearance at every lift height. See our Rubicon vs Sport vs Sahara comparison for more differences.

All-Terrain vs. Mud-Terrain: Choosing the Right Type

This is where most people overthink things. Here’s the honest breakdown.

All-Terrain (A/T) Tires

Best for: Daily drivers, occasional off-roading, highway miles, wet roads.

Pros:

Quieter on the highway
Longer tread life (40,000-60,000 miles)
Better wet traction on pavement
Lower rolling resistance = better fuel economy

Cons:

Less aggressive in deep mud
Can pack with mud in sticky conditions
Less sidewall protection

Popular choices: BFGoodrich KO2, Falken Wildpeak AT3W, Toyo Open Country AT3

Mud-Terrain (M/T) Tires

Best for: Serious off-roading, rock crawling, muddy trails, aggressive looks.

Pros:

Self-cleaning tread
Better grip in loose surfaces
Stronger sidewalls
Looks more aggressive (if that matters to you)

Cons:

Loud on the highway
Shorter tread life (25,000-40,000 miles)
Worse wet traction on pavement
Higher rolling resistance

Popular choices: BFGoodrich KM3, Nitto Trail Grappler, Toyo Open Country MT

The Honest Truth

If you’re 80% street, 20% trail: Get all-terrains. The KO2 is the go-to for a reason.

If you’re 50%+ off-road or hit serious mud: Mud-terrains make sense.

If you want the look but mostly drive pavement: You’re paying extra in noise, tread life, and fuel economy. Your call.

Popular Wheel and Tire Combos

These combinations are proven to work well on JKs.

The Daily Driver: 33s on Stock Height

Tires: 285/70R17 (BFGoodrich KO2)
Wheels: 17x8.5, 4.75” backspacing
Lift: None to 2”
Total cost: $1,200-1,800 (tires + wheels)

Great balance of capability and daily driving. No regear needed.

The Sweet Spot: 35s on 2.5” Lift

Tires: 35x12.50R17 (your choice of A/T or M/T)
Wheels: 17x9, 4.5” backspacing
Lift: 2.5-3.5”
Total cost: $2,500-4,000 (including lift, tires, wheels)

This is the most popular JK build for good reason. Significant improvement in capability without major drivetrain modifications. May want 4.88 gears if you have the 3.21 ratio.

The Serious Build: 37s on 4” Lift

Tires: 37x12.50R17
Wheels: 17x9, 4.5” backspacing
Lift: 4”+ with flat or high-line fenders
Total cost: $6,000-10,000+ (lift, gears, tires, wheels, fenders)

This is where costs escalate. You’ll need regearing (4.88s minimum), possibly upgraded axle shafts, and definitely fender modifications.

Regearing: When You Need It

Bigger tires act like a taller gear ratio, making your engine work harder. Here’s when regearing becomes necessary.

Regear Recommendations by Tire Size

Tire Size	Stock 3.21 Gears	Stock 3.73 Gears	Stock 4.10 (Rubicon)
33”	Consider 4.10	Fine	Fine
35”	Need 4.88	Consider 4.56	Usually fine
37”	Need 5.13	Need 4.88	Need 4.88

Signs You Need to Regear

Sluggish acceleration, especially on hills
Constantly downshifting (auto) or lugging in high gears (manual)
Significantly worse fuel economy than expected
Transmission running hot

Regear Cost

Expect $1,500-2,500 for parts and labor to regear both axles. This includes new ring and pinion gears, installation, and setup. Not a DIY job unless you have experience - gear setup requires precision.

The Real Cost of Bigger Tires

Let’s be honest about what larger tires actually cost beyond the sticker price.

33-Inch Tires

Item	Cost
Tires (set of 5)	$800-1,200
Wheels (set of 5)	$600-1,200
Lift (optional)	$0-500
Regear	Usually not needed
Total	$1,400-2,900

Ongoing: Minimal impact on fuel economy (maybe 0.5 mpg). Normal tire life.

35-Inch Tires

Item	Cost
Tires (set of 5)	$1,200-1,800
Wheels (set of 5)	$800-1,500
Lift kit	$500-2,500
Regear (if needed)	$0-2,500
Fender trimming	$0-200
Total	$2,500-8,500

Ongoing: 1-2 mpg loss. Increased wear on steering and suspension components. Slightly shorter tire life.

37-Inch Tires

Item	Cost
Tires (set of 5)	$1,800-2,500
Wheels (set of 5)	$800-1,500
Lift kit	$2,000-4,500
Regear	$1,500-2,500
Fenders	$400-800
Axle upgrades (maybe)	$0-2,000
Total	$6,500-13,800

Ongoing: 2-3 mpg loss. Accelerated wear on axles, U-joints, and wheel bearings. Increased stress on transmission.

Common Mistakes to Avoid

Buying wheels with too much backspacing: Stock-backspacing wheels push the tire inward, causing inner fender rubbing with larger tires.

Ignoring wheel width: A 12.50-inch-wide tire on a 7-inch-wide wheel will bulge excessively. Match wheel width to tire width (9” wheel for 12.50” tire is ideal).

Cheaping out on tires: Your tires are the only thing between your Jeep and the ground. Budget $200+ per tire for quality rubber.

Forgetting the spare: Five tires, five wheels. Your spare matters, especially off-road.

Skipping the alignment: After any wheel/tire change, get an alignment. It’s $100 that saves you from uneven tire wear.

Recommended Wheel Brands

Brand	Price Range	Notes
Method Race	$250-350/wheel	Popular, proven, wide selection
Fuel	$200-300/wheel	Aggressive styles, good quality
Pro Comp	$150-250/wheel	Budget-friendly, decent quality
Mopar	$200-350/wheel	OEM quality, conservative styles
Black Rhino	$200-300/wheel	Good value, stylish
KMC	$180-280/wheel	Solid mid-range option

Best JK Lift Kits - Choosing the right lift for your tire size
Rubicon vs Sport vs Sahara - Stock differences that affect fitment
JK Death Wobble: Causes and Fixes - Wheel and tire balance matters
The Complete JK Buyer’s Guide - Consider tire size when budgeting your purchase

Frequently Asked Questions

What size tires fit a stock JK?

Stock JKs can fit up to 33x10.50 tires with no modifications. 33x12.50 may require minor trimming of the fender liner and removing the air dam. Rubicons with their higher fenders can fit 33s more easily than Sport or Sahara models. For anything larger, you’ll need a lift.

What wheel backspacing do I need?

For JKs, 4.5-inch backspacing (or about -12mm offset) is the sweet spot for most tire sizes up to 35s. This pushes the tires out slightly for better inner fender clearance while maintaining acceptable steering geometry. Going lower than 4” backspacing puts extra stress on wheel bearings.

Are 35-inch tires worth it?

35s offer noticeably better off-road capability with approximately 1 inch more ground clearance and improved approach/departure angles. However, they require at least a 2.5-inch lift, may need regearing (especially with 3.21 gears), and impact fuel economy by 1-2 mpg. For serious off-roading, absolutely worth it. For mostly pavement driving, 33s provide 90% of the benefit with fewer compromises.

Do I need to regear with 35-inch tires?

It depends on your current gear ratio. With Rubicon 4.10 gears, 35s are manageable without regearing, though 4.88s will feel better. With 3.73 gears, you can get by but will notice sluggishness. With 3.21 gears, regearing to 4.88 is strongly recommended for anything over 33s.

What’s the difference between offset and backspacing?

Both describe where the wheel mounting surface sits, just measured differently. Backspacing is measured in inches from the mounting surface to the wheel’s inner edge. Offset is measured in millimeters from the wheel centerline to the mounting surface. For JKs, 4.5” backspacing equals roughly -12mm offset on a 17x9 wheel.

Can I run different size tires front and rear?

Technically yes for 2WD driving, but it’s not recommended. When in 4WD with mismatched tire sizes, the transfer case binds because the axles turn at different speeds. Always run matching tires on all four corners (and your spare).