Is a 315/70R17 tire a good fit for your stock Jeep Wrangler? Many Jeep owners dream of bigger tires for a bolder look and better off-road performance.
But before you switch, you need to know if this size will fit your Wrangler without problems.
This guide breaks down everything you need to consider, with clear answers for both beginners and experienced Jeep drivers.
What Does 315/70r17 Mean?
The tire size 315/70R17 has three key parts:
- 315: Tire width in millimeters (about 12.4 inches)
- 70: Sidewall height as a percentage of width (70% of 315 mm)
- R17: Designed for a 17-inch rim
This size is close to a 35-inch tire, which is much larger than the stock Jeep Wrangler tire.
1. Stock Jeep Wrangler Tire Size
Most stock Jeep Wranglers use 245/75R17 or 255/70R18 tires. These are about 31–32 inches tall. The 315/70R17 is much wider and taller, so fitting them is not as simple as just mounting new tires.
2. Wheel Well Clearance
315/70R17 tires are about 34.4 inches in diameter. On a stock Jeep, this larger size can cause rubbing inside the wheel well, especially when turning or flexing the suspension.
3. Fender And Body Contact
Without any modifications, these tires often touch the fenders and plastic liners during normal driving. This can damage both the tires and the vehicle’s body over time.
4. Suspension And Lift Requirements
To fit 315/70R17 tires, you usually need a 2-inch or greater suspension lift. This gives the tires enough room to move up and down without hitting the Jeep’s body.
5. Wheel Backspacing
Stock Wrangler wheels have around 6 inches of backspacing. For 315/70R17 tires, less backspacing (about 4.5–5 inches) is better. This moves the wheel out, giving more space for the wider tires.
6. Tire Width And Turning Radius
Wider tires can reduce your turning radius. You might notice the steering feels heavier, and the wheels may rub on the sway bar or control arms.
7. Speedometer And Odometer Accuracy
Larger tires change your speedometer reading. When you drive 60 mph, your actual speed may be higher because the tires cover more ground per revolution. You may need a programmer to recalibrate your Jeep’s speed sensor.
8. Fuel Economy Impact
Bigger, heavier tires like the 315/70R17 can lower your fuel economy. Expect to lose 1–3 miles per gallon, depending on your driving habits.
9. Acceleration And Power Loss
These tires are heavier and have a larger rolling diameter. Many Jeep owners notice a loss in acceleration and slower throttle response, especially with the stock gear ratio.
10. Gear Ratio Considerations
If your Jeep has a stock gear ratio (like 3.21 or 3.73), 315/70R17 tires can strain the engine and transmission. Upgrading to a 4.10 or 4.56 gear ratio is recommended for best performance.
11. Braking Distance
Heavier tires can increase braking distance. Your Jeep may take longer to stop, especially in emergencies. Upgraded brakes are a smart safety upgrade.
12. Off-road Performance
On trails, the larger 315/70R17 tires give you more ground clearance and better grip on rocks or mud. But they can also make the steering feel less precise, especially on narrow trails.
13. On-road Handling
These tires add weight and width, which can make highway driving feel less stable. You might notice more road noise, vibration, and wandering at higher speeds.
14. Spare Tire Fitment
A 315/70R17 spare often will not fit on the stock spare tire carrier. The tire is heavier and may block your rear view or damage the tailgate. Many Jeep owners buy a reinforced tire carrier.
15. Legal And Warranty Concerns
Some areas have laws about tire size and tire coverage. Fitting 315/70R17 tires without fender flares may be illegal in certain states. Also, check if changing tire size affects your Jeep’s warranty.
16. Insurance Implications
Bigger tires can affect insurance rates or coverage if they contribute to an accident. Always tell your insurance company about major modifications to stay protected.
17. Cost Of Upgrades
Switching to 315/70R17 tires often means more than just buying tires. You may need new wheels, a lift kit, speedometer recalibration, and possibly reinforced parts. The total cost can easily exceed $2,000–$3,000.
Comparison: Stock Vs. 315/70r17 Tire Specs
Here’s a quick look at the differences between a typical stock tire and a 315/70R17:
| Feature | Stock Tire (245/75R17) | 315/70R17 |
|---|---|---|
| Diameter | 31.5 inches | 34.4 inches |
| Width | 9.6 inches | 12.4 inches |
| Weight (avg.) | 40 lbs | 60 lbs |
| Lift Needed? | No | Yes (2″+) |
Real-world Example
A Jeep owner with a stock 2021 Wrangler Rubicon tried 315/70R17 tires. The result? The tires rubbed on the fenders during turns and when off-roading. After installing a 2.5-inch lift and wheels with 4.75-inch backspacing, the tires fit well and performed great on trails.
Common Mistakes To Avoid
- Skipping the lift kit: Without lifting, tire rubbing is almost guaranteed.
- Ignoring backspacing: Using stock wheels with wide tires leads to rubbing on suspension parts.
- Forgetting about the spare: The spare must match your main tires for safe 4WD use.
- Not recalibrating electronics: Speedometer and transmission can be thrown off by tire size changes.
- Neglecting insurance and legal rules: Always check local laws and tell your insurer.
Cost Breakdown For 315/70r17 Upgrade
| Upgrade Item | Estimated Cost |
|---|---|
| Set of 5 Tires | $1,200–$1,800 |
| Lift Kit | $500–$1,500 |
| Wheels (set of 5) | $600–$1,000 |
| Recalibration Tool | $150–$250 |
| Reinforced Carrier | $200–$500 |
Should You Run 315/70r17 On A Stock Jeep Wrangler?
If you want bigger tires for style or off-road use, 315/70R17s are a popular choice. But on a stock Jeep Wrangler, they do not fit well without upgrades. A lift kit, new wheels, and calibration are usually required. Skipping these steps leads to damage, poor handling, and safety risks.
Before you make the change, plan your budget and upgrades. Consider if you need your Jeep for daily driving or mostly off-road.
If you want a simple, trouble-free upgrade, stick to tires closer to stock size.
For more technical tire data, see this Tire Rack technical guide.
Frequently Asked Questions
Will 315/70r17 Tires Fit Without A Lift?
No, these tires will rub on a stock Jeep Wrangler. A lift of at least 2 inches is needed for proper fit.
Do I Need New Wheels For 315/70r17 Tires?
Yes, aftermarket wheels with less backspacing (4. 5–5 inches) are recommended for clearance.
How Does This Tire Size Affect Gas Mileage?
Expect to lose 1–3 mpg due to the larger, heavier tires.
Will My Speedometer Be Accurate?
No, your speedometer will read low. You need a recalibration tool to correct it.
Are 315/70r17 Tires Good For Daily Driving?
They offer more ground clearance but can reduce ride comfort, handling, and fuel economy for daily driving. Make sure you are ready for these changes before upgrading.
