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Will 40-inch tires fit a JK Wrangler Rubicon?
Fitment answer · Updated October 27, 2026
Short answer
Only as a dedicated build. JKs on 40s usually have a 4.5-inch or taller lift, cut or high-clearance fenders, upgraded axles and steering, and very deep gears. Expect a major investment.
Shop the gear for this build ↓ Tires, deflators and a compressor picked for this setup.
What you usually need
- A 4.5-inch or taller long-arm lift.
- High-clearance fenders or cutting, and bump stops.
- Stronger axles, steering and brakes.
Regearing
40s on a JK usually need 5.38 or deeper gears. Compare ratios in the Tire & Gear Calculator before you buy gears.
Compare
Gear for this build
- JK all-terrain tires (search) — Filter by your size and Load Range.
- Mud-terrain tires (search) — Louder on the highway; buy for real mud use.
- Staun tire deflators — Repeatable trail pressures.
- VIAIR 88P portable compressor — Air back up before the highway.
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FAQ
Can a JK Rubicon run 40s?
Yes, as a full build.
Will stock Rubicon axles hold up?
Many owners upgrade for 40s.
Is 37 a better target?
For most JKs, yes.
Check your numbers
Use the free Tire & Gear Calculator to see speedometer error, highway RPM and a regear target, or ask TekJeep AI on the homepage with your year, trim, lift and wheel specs.
Related guides: All-terrain & mud-terrain tires · JK 2.5" lift overview
More fitment answers: 35s on a JK with a 2.5" lift · 33s on a stock JK · 37s on a JK with a 3.5" lift · 35s on a JK with a 3.5" lift · 33s on a JK with a 2.5" lift · 37s on a JK with a 4" lift · 35s on a stock JK · 37s on a JK with a 2.5" lift
Fitment disclaimer: Clearance depends on exact tire size, wheel specs, suspension and how hard you flex. Confirm with your tire shop or installer before buying.
Tire size how-tos: How to read a tire size · Bolt pattern & backspacing · Regearing for bigger tires · Tire pressure after upsizing · Speedometer error · Rubbing fixes