Yittzy

Tire Size Calculator

Compare tire sizes, see dimension differences, and calculate speedometer correction.

Current Tire Size

Diameter:
31.5"
Width:
9.6"
Sidewall:
7.2"
Circumference:
98.9"
Revs/Mile:
641

New Tire Size

Diameter:
32.7"
Width:
11.2"
Sidewall:
7.9"
Circumference:
102.8"
Revs/Mile:
617

Comparison Results

+1.2"
Diameter Change
+1.6"
Width Change
+3.9%
Speedometer Error
+0.6"
Ground Clearance Change

Speedometer correction: When your speedometer reads 60 mph, your actual speed will be 62.4 mph. Consider a speedometer recalibration with a programmer or dealer visit.

Shop 285/70R17 Tires

Understanding Tire Sizes for Your Jeep

Upgrading tires is one of the first modifications most Jeep owners make. Bigger tires provide more ground clearance, better traction, and a more aggressive look. But choosing the right size requires understanding how tire measurements work and how they affect your vehicle.

Common Jeep Tire Upgrades

Wrangler JL/JK: Stock tires are typically 245/75R17 (31.5"). Popular upgrades include 285/70R17 (32.7"/33"), 315/70R17 (34.4"/35"), and 37x12.50R17 for lifted builds.
Gladiator JT: Similar to JL with 245/75R17 stock. Most owners upgrade to 33-35" tires with a 2-3" lift.
Cherokee XJ: Stock 225/75R15 (28.3"). A 3" lift allows 31" tires, while a 4.5"+ lift fits 33" tires.

When to Regear

As a general rule, if you increase tire diameter by more than 15% over stock, you should consider regearing your axles. This restores power delivery and fuel economy. For a Wrangler JK with 3.21 gears going to 35" tires, 4.56 gears are recommended. For 37" tires, 4.88 gears are the standard choice.