When it comes to upgrading or replacing your tires, one of the questions that pops up is can I switch from 235 to 245 tires? It’s a small change but it can make a big difference in your vehicle’s performance, safety and handling.
We’ll touch on related topics to give you a full understanding, including size compatibility, performance, safety, cost, installation and personal experiences.
Contents
Difference Between 245 and 235 Tires
The first number in a tyre size (e.g. 245 or 235) is the width in millimeters.
- 245 is 245mm wide.
- 235 is 235mm wide.
235 is 10mm narrower than 245.
Understanding Tire Sizing and Compatibility
When buying new tires you need to understand the tire sizing system. Tire sizes are a combination of numbers and letters like P235/65R17 or P245/60R17.
These numbers and letters represent specific measurements for the tire’s width, aspect ratio and diameter. Here’s a quick breakdown of what each part means:
- Width (235/245): The first number is the tire’s width in mm from sidewall to sidewall.
- Aspect Ratio (65/60): The second number is the tire’s aspect ratio which is the height of the tire’s sidewall as a percentage of its width.
- Diameter (17): The third number is the diameter of the wheel in inches the tire is designed to fit.
So now you know what each part means. Can you replace 235 with 245? The width difference might not seem much.
The Potential Issues and Considerations
It’s not just a matter of choosing a different number. There are several things to consider and potential issues:
- Fitment: Will the new tires fit in your wheel wells without rubbing?
- Speedo Accuracy: Changing tire sizes messes with your speedo and odometer.
- Handling and Performance: Different tire sizes change your car’s handling, traction and overall performance.
- Safety: Will the new tires compromise your car’s safety features.
Let’s get into it.
Fitment and Compatibility
First and foremost, will the new 245’s fit your vehicle? Here’s a table comparing 235 and 245 tire dimensions:
| Tire Size | Width (mm) | Aspect Ratio (%) | Diameter (inches) |
|---|---|---|---|
| 235 | 235 | 65 | 17 |
| 245 | 245 | 60 | 17 |
Diameter is the same, but width and aspect ratio changes. This could cause fitment issues if your wheel wells aren’t wide enough to accommodate the extra 10mm of width. To ensure proper fitment:
- Check Manufacturer Specifications: Always refer to your owner’s manual or manufacturer’s guidelines.
- Consult a Professional: A tire specialist can give you the lowdown and physically inspect your vehicle to check compatibility.
Impact on Speedometer and Odometer
Changing tire sizes can affect your speedometer and odometer readings. This is because the overall diameter of the tire changes and your speedometer will show incorrect speeds. For example:
- 235/65R17: circumference is 91.82 inches
- 245/60R17: circumference is 91.04 inches
That’s a 0.78 inch difference. Not much but it can add up. According to Tire Rack a small change in tire diameter can result in 1-2% error in speedometer readings. Use a speedometer calibration tool or consult with a professional to correct these mistakes.
Handling and Performance
Upgrading from 235 to 245 tires will change your car’s handling and performance. Here’s how:
- Wider Tires: Better grip and traction in dry conditions. Better cornering and stability.
- Aspect Ratio Change: Lower aspect ratio means shorter sidewall. Better handling but firmer ride.
According to the University of Michigan Transportation Research Institute, wider tires can reduce rolling resistance and improve fuel efficiency. But that’s offset by the added weight of wider tires.
Safety Considerations
Always safety first when modifying your vehicle. Replacing 235 tyres with 245 tyres will affect several safety aspects:
- Braking distance: Wider tyres will give better braking due to more road contact.
- Hydroplaning risk: Wider tyres will increase the risk of hydroplaning in wet conditions due to more surface area.
Make sure you choose tyres that suit your driving conditions and that your vehicle’s safety systems like ABS and traction control work with the new tyres.
Cost Implications
Price varies on:
- Tire Brand and Model: High end and performance tires are more expensive.
- Installation and Alignment: Recommended to get installed and aligned professionally.
Here’s a comparative table of average tire costs:
| Tire Size | Average Cost per Tire | Installation Cost (per tire) | Total Cost for 4 Tires |
|---|---|---|---|
| 235 | $120 – $200 | $15 – $30 | $540 – $920 |
| 245 | $130 – $220 | $15 – $30 | $580 – $1,000 |
Note that prices can vary widely based on location and specific tire models.
Installation Process
Proper installation is key when changing tire sizes. Here’s how it’s done:
- Check: New tires must match your wheels and vehicle specs.
- Mount: Use a tire mounting machine to put the tires on the wheels.
- Balance: Balance the wheels to get rid of vibrations and smooth driving.
- Alignment: Check and adjust the vehicle’s alignment to prevent uneven tire wear.
Professional installation is safer and better.
Personal Experience and Insights
I went from 235 to 245’s on my SUV and noticed a big difference in handling and stability on highways and corners. But the ride was a bit firmer, took some getting used to. Consulting with a tire guy was worth it to make sure the new tires were a good fit and my speedometer was recalibrated.
Replacing 245-55-18 Tires with 235-55-18 Tires
Full tire size is width, aspect ratio (second number) and diameter of the wheel (last number):
- 245-55-18 means 245mm wide, 55% of width is the aspect ratio and fits 18 inch wheel.
- 235-55-18 means 235mm wide, 55% of width is the aspect ratio and fits 18 inch wheel.
Key points to consider:
- Width: 235 tire is 10mm narrower. This will affect handling, traction and appearance slightly.
- Aspect Ratio and Diameter: Both sizes have the same aspect ratio and wheel diameter so the overall diameter of the tire will be very similar. This means your speedometer reading, ground clearance and ride height will not be affected much.
- Load Rating and Handling: A narrower tire may have different load rating and may alter handling. Make sure the load rating of 235 tire is suitable for your vehicle.
Difference Between 235/65R17 and 245/65R17
- 235/65R17: 235mm wide with 65% of the width of the tire on the 17 inch wheel.
- 245/65R17: 245mm wide with 65% of the width of the tire on the 17 inch wheel.
Key differences:
- Width: 10mm wider
- Overall Diameter: Since the aspect ratio is a percentage of the width, the 245 tire will have a slightly larger overall diameter. About 6.5mm (10mm width difference 0.65 aspect ratio 2)
- Performance: Wider tire (245) may be better traction and stability, narrower tire (235) may be better fuel efficiency and less road noise.
Conclusion
You can change from 235 to 245 tyres and get better handling and grip. But you need to consider fitment, speedo accuracy, handling changes, safety and cost. Consult the experts and do your research and it will be a smooth transition and optimal performance.
If you’re thinking of making this change, remember to put safety first and consult with tyre specialists to make an informed decision. By understanding the implications and taking the necessary precautions you can get better driving experience with the right tyre upgrade.
References:
- Tire Rack. (n.d.). Understanding Tire Sizes. Retrieved from tirerack.com.
- University of Michigan Transportation Research Institute. (n.d.). Tire Width and Fuel Efficiency. Retrieved from umtri.umich.edu.
- National Highway Traffic Safety Administration (NHTSA). (n.d.). Tire Safety. Retrieved from nhtsa.gov.
