Off-roading isn’t just about horsepower or suspension travel—your off road tires are what truly connect you to the terrain. Whether you’re conquering rocky mountain trails, rolling through desert sand, or crawling over muddy ruts, the right tire size makes a world of difference.
But here’s the catch: understanding off-road tire sizes isn’t always easy. There’s a jungle of numbers, ratios, and codes to sort through. So how do you choose the right off-road tire size for your vehicle without making a costly mistake?
In this guide, we break it all down—from size formats to fitment tips, and everything in between—so you can upgrade with confidence.
Why Tire Size Matters in Off-Roading
Off-road tires do more than just look aggressive. The size directly affects your vehicle’s:
- Ground clearance
- Traction
- Fuel efficiency
- Ride comfort and control
- Suspension performance
Choosing the right size means balancing performance, fitment, and safety.
Go too small, and you limit your off-road capability. Go too big without proper modifications, and you could damage your suspension, reduce steering clearance, or even rub holes in your wheel wells.
Understanding Off-Road Tire Size Formats
You’ll often see tire sizes written in two different formats:
Metric Sizing (Example: 265/70R17)
This is the standard sizing used by most OEM tires and many aftermarket all-terrain models.
Let’s break down 265/70R17:
- 265= Tire width in millimeters
- 70= Aspect ratio (sidewall height as a percentage of width; 70% of 265mm)
- R= Radial construction
- 17= Wheel diameter in inches
To understand total height, you must calculate the sidewall height twice (top and bottom), then add the wheel diameter.
Example:
Sidewall = 265mm × 0.70 = 185.5mm
Total diameter = 185.5mm × 2 + 432mm (17 inches) = ~803mm or about 31.6 inches
Flotation Sizing (Example: 33×12.50R15)
This is common for larger off-road and mud-terrain tires, often used on lifted trucks and SUVs.
- 33= Overall tire diameter in inches
- 50= Tread width in inches
- R15= Fits a 15-inch rim
This format is more intuitive for off-roaders because it tells you exactly how big the tire is.
How to Choose the Right Tire Size for Your Vehicle
There are three main factors you need to consider:
Clearance and Fitment
Before you throw on 35s or 37s, you need to know what fits without rubbing.
- Stock vehiclestypically handle up to a 31″–33″ tire
- Mild lifts (1–2.5″)may allow up to 33″–35″
- Big lifts (3”+)can fit 35” to 37”+, depending on the wheel well size and articulation
Check for:
- Fender clearance
- Wheel offset and backspacing
- Suspension compression (up-travel)
- Turning radius—watch for rub during full lock
If you go too big without adjusting these, you’ll risk tire rub, broken fenders, or steering issues.
Gear Ratios and Drivetrain
Larger SUV tires affect your final drive ratio, meaning you’ll lose torque and fuel efficiency unless you re-gear.
For example:
- Jumping from a 30” to 35” tirecan result in noticeable power loss
- Re-gearing your axles helps restore performance and reduces transmission stress
Intended Use
- Daily Driver with Weekend Trails?Stick with 31–33” all-terrain tires
- Overlanding and Mixed Terrain?Go with 33–35” tires for ground clearance and comfort
- Extreme Rock Crawling or Mud Bogging?Look at 35”–40” mud-terrain or competition tires, but expect major vehicle modifications
Tire Width vs. Sidewall: What’s More Important Off-Road?
Wider Tires
- Better flotationon sand and snow
- More sidewall contactfor rock crawling
- Can cause rubbing issues without proper wheel offset
Taller Sidewalls (Higher Aspect Ratio)
- More flex for rocks and uneven terrain
- Better shock absorption
- Riskier for daily highway speeds at low PSI
Off-roaders typically prefer a tall, narrow tire for rocks and snow, and a wide, soft tire for sand.
Real-World Tire Size Examples
Common Mistakes to Avoid When Sizing Up Tires
- Ignoring suspension limits– Oversized tires can bottom out or rub under flex
- Skipping re-gearing– Larger tires = slower acceleration and poor MPG
- Not checking wheel offset– Wrong backspacing = fender rub and steering strain
- Choosing tires too wide– Adds stress to drivetrain and may cause wandering at high speeds
Always consult your vehicle’s manual, forums, or a trusted off-road shop before buying.
Final Thoughts
Choosing the right off-road tire size is about more than just aggressive looks. The right size can enhance traction, boost comfort, and increase your vehicle’s capability—but only if it fits properly and matches your rig’s setup.
To get the best performance:
- Know your clearance limits
- Factor in your driving style and terrain
- Don’t sacrifice sidewall for wheel size
- Re-gear if you’re jumping to big rubber
With the right size under your truck or SUV, you’ll have the confidence to explore deeper, climb higher, and power through terrain that would leave others stuck.
