Tire Size 255/70r17 vs 285/70r17
Switching from 255/70R17 to 285/70R17 tires offers significant changes that impact both performance and aesthetics. Let’s explore these differences.
- Increased overall diameter enhances ground clearance
- Wider tires improve traction on various terrains
- Greater width may lead to improved stability during turns
- Larger sidewall height can enhance ride comfort
- Reduced revolutions per mile may affect speedometer accuracy
- Wider tires may cause increased road noise
- Potentially lower fuel efficiency due to increased rolling resistance
Fitment Guide
It is crucial to stay within a 3% difference in overall diameter from the original tire size. If the diameter difference exceeds this acceptable range, it is generally not recommended to proceed with the switch due to the risk of fitment issues.
For the 255/70R17 and 285/70R17, the difference in diameter exceeds this limit at 5.3%, indicating that careful consideration and potential vehicle modifications would be needed.
If you still opt for this change, adaptations like lifting or trimming might be necessary to prevent issues such as rubbing or clearance problems.
On-Road Impact
Switching to 285/70R17 from 255/70R17 brings changes that influence various aspects of on-road performance. Below, we’ll examine how these two tire sizes compare in terms of gas mileage, ride comfort, speedometer accuracy, and more.
Gas Mileage
Larger tires often require more energy to turn due to their increased weight and surface area. As a result, switching to 285/70R17 can negatively affect gas mileage.
The increased rolling resistance of the wider 285 tire means your engine must work harder, leading to reduced fuel efficiency. This impact is more pronounced in city driving where stop-and-go situations are common.
Ride Comfort
With the change to a larger sidewall height (7.85 inches compared to 7.03 inches), the 285/70R17 can offer a smoother ride due to increased cushioning.
The taller sidewall allows for more absorption of road imperfections, leading to better comfort for passengers on uneven surfaces.
However, the extra width can make the tire more prone to tracking road grooves, potentially decreasing comfort in some situations.
Speedometer Accuracy
A significant aspect of changing tire size is how it affects your speedometer reading. With the 285/70R17, your vehicle’s speedometer will underreport your speed.
For instance, if your speedometer reads 20 mph, your actual speed will be approximately 21.06 mph. This discrepancy arises from the larger diameter, which means fewer revolutions per mile compared to the original 255/70R17 tire.
Durability & Wear
The larger contact patch of the 285/70R17 can lead to more even wear, provided that the tires are kept properly inflated and aligned.
However, the increased width also means a higher risk of accelerated wear if the vehicle’s suspension is not adjusted accordingly. Proper alignment is crucial to ensure even distribution of wear across the tire’s surface.
Aesthetics Look
The wider 285/70R17 provides a more aggressive stance, giving the vehicle a rugged, off-road-ready appearance. The increased width and height create a bolder aesthetic that many off-road enthusiasts prefer.
However, this change may not suit all vehicle types, particularly if a sleeker, more aerodynamic look is desired.
Off-Road Impact
Off-road conditions demand tires that can handle various terrains, and switching to a larger tire can significantly alter your vehicle’s off-road capabilities. Let’s look at how this switch affects ground clearance, traction, and vehicle capability.
Ground Clearance
The increased diameter of the 285/70R17 tire raises the vehicle’s ground clearance by approximately 0.83 inches compared to the 255/70R17.
This added clearance can make a significant difference when tackling off-road obstacles like rocks or deep ruts, allowing the vehicle to pass over terrain that might have posed a challenge with the smaller tire size. However, increased height may also raise the vehicle’s center of gravity, potentially affecting stability.
Traction
With a wider tread, the 285/70R17 provides better traction, especially in loose or muddy terrain. The larger contact area improves grip, making it easier to navigate difficult off-road conditions.
This can be especially useful when driving through sand, mud, or snow, where a larger surface area can help prevent the vehicle from getting stuck.
Vehicle Capability
The switch to a larger tire can enhance the vehicle’s off-road capability by providing better approach and departure angles.
However, the increased weight of the 285/70R17 can put additional stress on the drivetrain, suspension, and braking system, potentially requiring upgrades to these components to handle the added load effectively. Ensuring that the vehicle’s suspension is up to the task is critical to maintaining its off-road performance.
255/70r17 vs 285/70r17
This table compares the key features of the 255/70R17 and 285/70R17 tire sizes.
| Feature | 255/70R17 | 285/70R17 | Difference |
|---|---|---|---|
| Diameter inches (mm) | 31.06 (788.8) | 32.71 (830.8) | 1.65 (42) +5.3% |
| Width inches (mm) | 10.04 (255) | 11.22 (285) | 1.18 (30) +11.8% |
| Circumference inches (mm) | 97.56 (2478.09) | 102.76 (2610.04) | 5.19 (131.95) +5.3% |
| Sidewall Height inches (mm) | 7.03 (178.5) | 7.85 (199.5) | 0.83 (21) +11.8% |
| Revolutions per mile (km) | 649.43 (403.54) | 616.60 (383.14) | -32.83 (-20.4) -5.1% |
| Speedo Reading | 20 mph | 21.06 mph | +1.06 mph |
Difference Between 255/70R17 and 285/70R17
The main difference between 255/70R17 and 285/70R17 tires is their width; the 285 tire is wider by 1.18 inches (30 mm), providing more surface area for traction.
How Much Taller Is a 285/70R17 Tire Than a 255/70R17?
A 285/70R17 tire is approximately 1.65 inches (42 mm) taller than a 255/70R17 tire, increasing the overall diameter by about 5.3%.
How Much Wider Is a 285/70R17 Tire Than a 255/70R17?
A 285/70R17 tire is about 1.18 inches (30 mm) wider than a 255/70R17 tire, resulting in an 11.8% increase in width.
Can I Use 285/70R17 Instead of 255/70R17?
Using 285/70R17 tires instead of 255/70R17 is not recommended due to the size difference exceeding 3%. The 285 size is 1.65 inches taller and 1.18 inches wider, which may require modifications to avoid clearance issues.
Our Observation
Switching from 255/70R17 to 285/70R17 has both benefits and drawbacks that are worth considering, depending on your intended use.
On-road, the increased tire size brings a more aggressive look and improved ride comfort due to the taller sidewalls, but at the cost of reduced gas mileage and speedometer inaccuracy.
These differences can be noticeable during daily commutes, especially in terms of fuel consumption and handling in tight turns. Off-road, the added ground clearance and improved traction significantly enhance the vehicle’s capability to handle rugged terrains.
However, the larger size and increased weight may necessitate modifications to avoid rubbing issues and ensure the vehicle’s suspension and drivetrain are capable of managing the additional stress.
Overall, if you frequently drive off-road or value a bolder aesthetic, the switch to 285/70R17 may be worth the trade-offs. For primarily on-road use, though, the downsides in gas mileage and handling might outweigh the benefits.
Asma Akter is the lead writer at Tiresizecompare.com, bringing her expertise to the automotive industry. With a strong background in technical writing and a passion for clear communication, Asma excels at breaking down complex tire-related information for readers. Her work helps consumers make informed decisions about tire sizes and compatibility, contributing to safer and more efficient vehicle operations.
