A Jeep Wrangler JL on stock Sport/Sahara trim (245/75R17, 30.5 in) can fit 33-inch tires (285/70R17) without any lift. With a 2–2.5-inch lift, 35-inch tires (285/75R17) bolt on cleanly. With a 3.5–4-inch lift and high-clearance fender flares, 37-inch tires (37×12.5R17) fit the JL Rubicon. Each step up in tire size requires re-gearing: 4.10 axle gears for 33-inch, 4.56 for 35-inch, 4.88–5.13 for 37-inch and above.
Jeep Tire Size Calculator
OEM sizes, max fitment by lift, gear ratio recommendations, crawl ratio, metric ↔ inch conversion, and speedometer correction — all Wrangler, Gladiator, Cherokee, and Grand Cherokee generations covered.
QUICK EXAMPLE
A stock 2024 Jeep Wrangler JL Sport rolls off the factory floor on 245/75R17 tires — a modest 30.47-inch overall diameter. Most owners are surprised to learn that simply bolting on a set of 285/70R17 tires (32.71 in) clears the stock fenders without any lift, adds nearly 2.25 inches of ground clearance, and costs nothing beyond the tires themselves. Push to a 285/75R17 (32.83 in) on the same stock suspension and the front fender flares will scuff at full articulation on the JL Sport — but clear perfectly on the Rubicon, which has high-clearance flares from the factory. The gear ratio question is where most first-timers get burned: jumping from stock 30.5 to 35-inch tires on the common 3.45:1 JL Sahara axle ratio kills low-end torque and highway fuel economy. The community-proven fix is a 4.56:1 re-gear, which restores the original rpm-per-mph ratio almost exactly. Use the calculator above to verify your exact combination before ordering parts.
OEM Tire Size Lookup — JL, JK, TJ, YJ, Gladiator, Cherokee, Grand Cherokee
OEM Tire Size
285/70R17
Rear (if diff)
Same as front
Stock Gear Ratio
4.10
Bolt Pattern
5×127 (5×5″)
Rim Size (stock)
17×7.5
Generation
JL
Maximum Tire Size by Lift Level
Stock / No Lift
35″
2–2.5″ Lift
37″
3.5–4″+ Lift
38–40″
OEM Tire Dimensions — 285/70R17
Total Height
32.71″
Sidewall
7.85″
Circumference
102.76″
Revs / Mile
617
Model Notes
Locker-equipped; HC fender flares standard; best starting point for 37s
Load this model's stock size into the comparison tab:
OEM Tire Reference — All Jeep Models & Generations
| Model | Gen | OEM Size | Height (in) | Stock Gear | Bolt Pattern | Max (no lift) | Max (2–2.5″) |
|---|---|---|---|---|---|---|---|
| JL | 245/75R17 | 31.47″ | 3.45 | 5×127 (5×5″) | 33″ | 35″ | |
| JL | 255/75R17 | 32.06″ | 4.10 | 5×127 (5×5″) | 33″ | 35″ | |
| JL | 255/70R18 | 32.06″ | 3.45 | 5×127 (5×5″) | 33″ | 35″ | |
| JL | 285/70R17 | 32.71″ | 4.10 | 5×127 (5×5″) | 35″ | 37″ | |
| JK | 245/75R16 | 30.47″ | 3.21 | 5×127 (5×5″) | 32″ | 33″ | |
| JK | 255/75R17 | 32.06″ | 4.10 | 5×127 (5×5″) | 33″ | 35″ | |
| TJ | 215/75R15 | 27.70″ | 3.07 | 5×114.3 (5×4.5″) | 30″ | 31–32″ | |
| TJ | 245/75R16 | 30.47″ | 4.10 | 5×114.3 (5×4.5″) | 31″ | 33″ | |
| YJ | 205/75R15 | 27.11″ | 3.07 | 5×114.3 (5×4.5″) | 29–30″ | 31–32″ | |
| JT | 245/75R17 | 31.47″ | 3.45 | 5×127 (5×5″) | 33″ | 35″ | |
| JT | 285/70R17 | 32.71″ | 4.10 | 5×127 (5×5″) | 35″ | 37″ | |
| WJ | 235/65R17 | 29.03″ | 3.07 | 5×127 (5×5″) | 30″ | 31″ | |
| WK2 | 265/60R18 | 30.52″ | 3.07 | 5×127 (5×5″) | 30–31″ | 32″ | |
| KJ | 225/75R16 | 29.29″ | 3.07 | 5×114.3 (5×4.5″) | 29″ | 30–31″ | |
| KL | 225/60R17 | 27.63″ | 3.73 | 5×114.3 (5×4.5″) | 28″ | 29″ |
Click any model name to load its full specs above. Max sizes are typical community-vetted limits — results vary by offset, wheel width, and driving style.
How to Use This Calculator
- 1Tab 1 — OEM Lookup: Select your Jeep model from the dropdown (JL, JK, TJ, YJ, JT, WJ, WK2, KJ, KL). The calculator instantly shows your factory tire size, overall diameter, bolt pattern, stock axle gear ratio, and the three fitment tiers: stock-clearance max, 2–2.5″ lift max, and 3.5–4″ lift max.
- 2Tab 2 — Size Converter: Enter any metric tire code (e.g. 285/75R17) or any inch-format floatation size (e.g. 37×12.5R17). The calculator cross-converts between both formats, shows overall diameter, circumference, revs/mile, and displays a fitment badge (Stock Fit / Bolt-On / Lift Required / Major Build) for each common Jeep model.
- 3Tab 3 — Gear Ratio: Enter your current tire diameter, your proposed new tire diameter, and your current axle gear ratio. The calculator outputs the recommended new ratio to restore your original rpm-per-mph, the rpm delta at 65 mph, the speedometer correction factor, and a per-speed table from 25–85 mph. Re-gear alert fires if the correction exceeds 8%.
- 4Tab 4 — Reverse Lookup: Enter a target tire diameter in inches and your rim size. The calculator returns all standard metric sizes within ±1.5% plus all common floatation inch sizes at that diameter — sorted by closest match, with a "compatible Jeep models" note per size.
- 5Tab 5 — Crawl Ratio: Select your transfer case (Rock-Trac NV241OR, Command-Trac NV241, Selec-Trac, etc.) and transmission (ZF 8HP, NSG370, BA10/5, AX5). The calculator outputs your full crawl ratio chain: 1st-gear × t-case low × axle ratio, with a benchmark comparison against stock Rubicon (84.2:1) and the community "trail minimum" of 50:1.
- 6Global: Toggle Metric/Imperial (top right) to switch force and speed display. Click "Copy Results" to copy a formatted summary to your clipboard. Use "Load Preset" to quick-fill a known factory drivetrain configuration.
Jeep OEM Tire Sizes — All Models Reference
| Model | Years | Trim | OEM Size | Height | Bolt Pattern | Stock Gears | Notes |
|---|---|---|---|---|---|---|---|
| JL Wrangler | 2018–2026 | Sport / Sport S | 245/75R17 | 30.47″ | 5×127 | 3.45:1 | Stock flares — 33″ clears w/o lift |
| JL Wrangler | 2018–2026 | Sahara | 255/75R17 | 30.47″ | 5×127 | 3.45:1 | Same height as Sport; wider tread |
| JL Wrangler | 2018–2026 | Rubicon | 285/70R17 | 32.71″ | 5×127 | 4.10:1 | Hi-clearance flares; 35″ bolt-on |
| JL Wrangler | 2020–2026 | Rubicon 392 (V8) | 315/70R17 | 34.36″ | 5×127 | 4.56:1 | 35″ OEM on factory clearance |
| JT Gladiator | 2020–2026 | Sport | 255/75R17 | 30.47″ | 5×127 | 3.45:1 | Pickup bed limits fender mods |
| JT Gladiator | 2020–2026 | Rubicon | 285/70R17 | 32.71″ | 5×127 | 4.10:1 | 35″ with 2″ lift; 37″ w/ 3.5″ |
| JK Wrangler | 2007–2018 | Sport / Sahara | 245/75R17 | 30.47″ | 5×127 | 3.73:1 | 33″ bolt-on; 35″ needs 2.5″ lift |
| JK Wrangler | 2007–2018 | Rubicon | 255/75R17 | 31.07″ | 5×127 | 4.10:1 | 35″ with 2″ lift; 37″ w/ 3.5″ |
| TJ Wrangler | 1997–2006 | Sport / SE | 215/75R15 | 27.74″ | 5×114.3 | 3.73:1 | 33″ fits w/ 2″ lift (narrow axle) |
| TJ Wrangler | 1997–2006 | Rubicon | 245/75R16 | 29.53″ | 5×114.3 | 4.11:1 | 35″ w/ 2.5–3″ lift; check D44 clearance |
| YJ Wrangler | 1987–1995 | All | 215/75R15 | 27.74″ | 5×114.3 | 3.73:1 | Narrow leaf-spring; limit to 31–33″ |
| WJ Grand Cherokee | 1999–2004 | Laredo | 225/75R16 | 28.37″ | 5×127 | 3.55:1 | Unibody — limit to 31″ max |
| WK2 Grand Cherokee | 2011–2022 | Trailhawk | 265/60R18 | 30.51″ | 5×127 | 3.45:1 | Air suspension; 33″ needs spacer |
| KL Cherokee | 2014–2023 | Trailhawk | 225/65R17 | 28.52″ | 5×114.3 | 3.64:1 | Unibody; 30″ practical max |
OEM sizes sourced from Jeep factory build sheets and Mopar documentation. Bolt pattern critical — TJ/YJ use 5×114.3 mm; JK/JL/JT/WJ/WK2 use 5×127 mm. Not interchangeable without adapters.
Max Tire Size by Lift Level
| Model | Stock (0″ lift) | 2–2.5″ Lift | 3.5–4″+ Lift | Notes |
|---|---|---|---|---|
| JL Sport/Sahara | 33″ (285/70R17) | 35″ (285/75R17) | 37″ (315/70R17 or 37×12.5R17) | Add hi-clearance flares at 37″ |
| JL Rubicon | 35″ (285/70R17 — OEM) | 37″ (315/70R17) | 38–40″ with flare mods | Hi-clearance flares already fitted |
| JK Sport/Sahara | 33″ (285/70R17) | 35″ (285/75R17) | 37″ (315/70R17) | May need flare swap at 37″ |
| JK Rubicon | 33–35″ | 37″ (315/70R17) | 38–40″ with flare mods | 4.10 factory gears; re-gear at 37″+ |
| JT Gladiator Rubicon | 35″ (OEM) | 37″ (315/70R17) | 37–40″ with mods | Pickup bed limits rear clearance |
| TJ Sport/SE | 30–31″ (30×9.5R15) | 33″ (30×9.5R15) | 35″ — watch D35 limits | Narrow TJ portal clearance concern |
| TJ Rubicon | 31–33″ | 35″ (30×9.5R15 or 285/75R16) | 35–37″ with SYE | Dana 44 front handles 37″ well |
Clearances assume stock wheel offset. Negative offset wheels push tires outward and may require additional fender clearance checks. Rubbing at full articulation may still occur — always verify on your specific build before final tire selection.
Gear Ratio Recommendations by Tire Size
| Tire Range | Example Sizes | Axle Ratio | RPM @ 65 mph | Verdict |
|---|---|---|---|---|
| 30–31″ | 245/75R17 (stock JL) | 3.21–3.45 | ~2,700 rpm @ 65 mph | Stock — no re-gear needed |
| 32–33″ | 285/70R17, 33×10.5R15 | 3.73 | ~2,650 rpm @ 65 mph | Ideal upgrade from 3.45 stock |
| 33–34″ | 285/75R16, 33×12.5R15 | 4.10 | ~2,710 rpm @ 65 mph | JK/JL Rubicon factory ratio |
| 34–36″ | 315/70R17, 35×12.5R17 | 4.56 | ~2,720 rpm @ 65 mph | Community standard for 35″ builds |
| 36–38″ | 37×12.5R17, 37×13.5R20 | 4.88 | ~2,680 rpm @ 65 mph | Correct for most 37″ builds |
| 38–40″ | 40×13.5R17, 40×15.5R20 | 5.13–5.38 | ~2,700 rpm @ 65 mph | Required for 38″+ extreme builds |
RPM targets based on the ZF 8HP 8-speed automatic (6th-gear 1.00 direct, 7th 0.84, 8th 0.67) at 65 mph highway cruise. NSG370 6-speed manual and BA10/5 5-speed values will differ slightly. Community data sourced from Omix, ExtremeTerrain, and Mount Zion Off Road.
Formulas & Calculations
Jeep Tire Size & Gear Ratio Formulas — Complete Reference
1. OVERALL TIRE DIAMETER FROM P-METRIC CODE (e.g. 285/75R17)
Step 1 — Sidewall Height (mm):
Sidewall_mm = Section Width × (Aspect Ratio ÷ 100)
= 285 × 0.75 = 213.75 mm
Step 2 — Sidewall Height (inches):
Sidewall_in = 213.75 ÷ 25.4 = 8.41 in
Step 3 — Overall Diameter:
OD = Rim_Diameter + 2 × Sidewall_in
= 17 + 2 × 8.41 = 33.83 in (859.3 mm)
2. OVERALL DIAMETER FROM INCH-FORMAT SIZE (e.g. 35×12.5R17)
OD = Nominal tire diameter in inches = 35.00 in (nominal; actual may be 34.7–35.0 in)
Note: floatation inch sizes quote the nominal inflated diameter directly.
3. CIRCUMFERENCE
C = π × OD = 3.14159 × 33.83 = 106.29 in (2,700 mm)
4. REVOLUTIONS PER MILE
Rev/Mile = 63,360 ÷ C_in = 63,360 ÷ 106.29 = 596 rev/mi
5. RECOMMENDED GEAR RATIO (RE-GEAR FORMULA)
New_Ratio = Old_Ratio × (New_Tire_OD ÷ Old_Tire_OD)
Example — upgrading from 245/75R17 (30.47 in) to 285/75R17 (33.83 in) on 3.45 stock:
New_Ratio = 3.45 × (33.83 ÷ 30.47) = 3.45 × 1.110 = 3.83
→ Rounds up to the available 4.10 ratio for a slight torque advantage.
6. SPEEDOMETER CORRECTION
True_Speed = Indicated_Speed × (New_OD ÷ Old_OD)
Example — 285/75R17 on stock JL (30.47 OEM):
True_Speed @ 60 mph indicated = 60 × (33.83 ÷ 30.47) = 66.6 mph actual
(speedometer reads ~10% LOW — correction mandatory before road use)
7. CRAWL RATIO
Crawl_Ratio = 1st_Gear_Ratio × T-Case_Low_Ratio × Axle_Gear_Ratio
Example — JL Rubicon (ZF 8HP 8-speed):
1st gear = 4.71 × Rock-Trac low (4.00:1) × 4.10 axle = 77.3:1
Example — JK Rubicon (NSG370 6MT):
1st gear = 4.46 × Rock-Trac low (4.00:1) × 4.10 axle = 73.1:1
Community trail minimum: 50:1. Rock-crawling benchmark: 70:1+.
8. AXLE RATIO QUICK-ESTIMATE (OMIX COMMUNITY FORMULA)
Recommended_Ratio ≈ 0.12 × Tire_Diameter_in
Example — 35-inch tires: 0.12 × 35 = 4.20 → spec 4.10 or 4.56 (both available)
Example — 37-inch tires: 0.12 × 37 = 4.44 → spec 4.56
Example — 40-inch tires: 0.12 × 40 = 4.80 → spec 4.88 or 5.13
9. GROUND CLEARANCE GAIN PER INCH OF TIRE HEIGHT
ΔGround_Clearance = ΔTire_Diameter ÷ 2
Going from 30.47 in to 33.83 in: (33.83 − 30.47) ÷ 2 = +1.68 in ground clearance
10. BOLT PATTERN IDENTIFICATION
TJ (1997–2006) and YJ (1987–1995): 5×114.3 mm (5×4.5″)
JK (2007–2018), JL (2018–present), JT (2020–present): 5×127 mm (5×5.0″)
WJ/WK/WK2 Grand Cherokee: 5×127 mm (5×5.0″)
KJ/KL Cherokee: 5×114.3 mm (5×4.5″)
IMPORTANT: TJ/YJ wheels are NOT interchangeable with JK/JL/JT — verify before swapping.Understanding Jeep Tire Sizes
Jeep tire sizing uses two parallel conventions that coexist in the community. Modern Jeeps from the factory ship with P-metric codes like 285/70R17 — the same format used on all passenger vehicles — where the three numbers encode section width in millimetres, sidewall aspect ratio as a percentage, and rim diameter in inches. Off-road and aftermarket communities frequently use floatation inch sizes like 35×12.5R17, where the numbers directly state the nominal overall diameter, tread width in inches, and rim diameter. Both formats describe the same physical tire; the calculator above converts instantly between them.
The Lift, Tire, and Gear Ratio Triangle
The most expensive mistake Jeep owners make is upgrading one corner of this triangle without the others. Fitting 35-inch tires without a lift causes rubbing at full lock. Fitting a 3.5-inch lift and 37-inch tires without re-gearing from the JL Sahara’s stock 3.45 gears leaves you with sluggish acceleration, excessive drivetrain heat on trails, and noticeably worse highway fuel economy. The three components are mechanically linked: each inch of tire diameter increase demands proportional lift for clearance and a proportional gear ratio increase to restore the original torque multiplication at the wheels.
JL vs JK vs TJ — What Changed?
The JL Wrangler (2018–present) introduced wider fender flares, a wider wheelbase, and a significantly more capable stock suspension than the JK — allowing the JL Rubicon to ship with 285/70R17 as a factory tire, a size that required a 2-inch lift on the JK. The JK (2007–2018) shares the 5×127 mm bolt pattern with the JL, so wheel swaps are direct, but JK fender clearance is tighter. The TJ (1997–2006) and YJ (1987–1995) use the older 5×114.3 mm bolt pattern — a critical compatibility break that catches many buyers off guard when shopping used Jeep wheels. Always confirm bolt pattern before purchasing any wheels for a Jeep built before 2007.
Crawl Ratio — Why It Matters for Off-Road
Crawl ratio is the total mechanical advantage at the wheels in 4-Low, 1st gear — the product of first gear ratio, transfer-case low range, and axle gear ratio. A higher crawl ratio gives finer throttle control on slow technical terrain and reduces the risk of tire spin on loose rock. The stock JL Rubicon with Rock-Trac (4.00:1 low range), ZF 8-speed (4.71:1 first gear), and 4.10 axle gears produces a crawl ratio of approximately 77.4:1. The off-road community generally considers 50:1 a trail minimum and 70:1+ a rock-crawling benchmark. Re-gearing to 4.56 while keeping the same t-case and transmission raises crawl ratio to 86.1:1 — a meaningful gain on technical terrain.