Tire Size 285/75r17 vs 285/70r17

Switching from 285/75R17 to 285/70R17 tires involves a slight reduction in overall diameter and sidewall height. Let’s explore the implications of this tire size switch.

• Overall diameter decreases by 1.12 inches
• Sidewall height reduces by 0.56 inches
• Ground clearance lowers by approximately half an inch
• Speedometer will underreport actual speed by about 3.3%
• Tire rotations per mile increase by 20.45

285/75r17 vs 285/70r17 Table

The primary difference between 285/75R17 and 285/70R17 tires lies in their overall diameter.

Fitment Guide

The general rule is that replacement tires should be within plus or minus 3% of the original tire’s overall diameter. In this case, the diameter difference of -3.3% slightly exceeds this range.

While not drastically outside the guideline, this change may necessitate some adaptations to ensure proper fit and performance.

On-Road Impact

The switch to 285/70R17 tires will have several effects on your vehicle’s on-road performance. Let’s examine these impacts:

• Speedometer Accuracy: With the smaller diameter, your vehicle will actually be traveling slightly slower than the speedometer indicates. At a displayed speed of 20 mph, your actual speed will be about 19.34 mph. This difference becomes more pronounced at slower speeds, potentially affecting your perception of speed and fuel economy.
• Ride Comfort: The reduced sidewall height (from 8.42 to 7.85 inches) may result in a slightly firmer ride. You might notice increased sensitivity to road imperfections, though the difference may be minimal for many drivers.
• Gas Mileage: The smaller overall diameter means your engine will need to work slightly harder to maintain the same speed, potentially leading to a minor decrease in fuel efficiency. However, this difference is likely to be negligible in real-world driving conditions.
• Aesthetics: The 285/70R17 tires will give your vehicle a slightly lower stance. This might enhance the sporty appearance of some vehicles but may not be as noticeable on larger SUVs or trucks.

Off-Road Impact

For off-road enthusiasts, the tire size change will also affect performance in various terrains:

• Ground Clearance: The reduction in overall diameter will lower your vehicle’s ground clearance by approximately half an inch. While this might seem minor, it could make a difference when navigating over large rocks or deep ruts in challenging off-road situations.
• Traction: The slightly smaller tire may provide a marginal increase in traction due to a more concentrated contact patch. However, this difference is likely to be minimal and may not be noticeable in most off-road scenarios.
• Durability & Wear: The reduced sidewall height of the 285/70R17 tires might make them slightly more susceptible to damage from sharp rocks or other off-road hazards. However, modern tire construction techniques often mitigate this concern.

What is the Difference Between 285/75r17 and 285/70r17?

The main difference between 285/75r17 and 285/70r17 tires is in their overall diameter and sidewall height. The 285/70r17 tire is smaller in diameter by 1.12 inches (28.5 mm) and has a lower sidewall height by 0.56 inches (14.25 mm).

This results in a 3.3% reduction in overall diameter and a 6.7% decrease in sidewall height. The width remains the same for both tires at 11.22 inches (285 mm).

Can I Use 285/70r17 Instead of 285/75r17?

Using 285/70r17 instead of 285/75r17 is not typically recommended. The difference in diameter between these two tire sizes is 3.3%, which slightly exceeds the generally accepted 3% threshold for tire size changes.

This difference may affect vehicle performance, handling, and speedometer accuracy. While the change is close to the limit, it’s advisable to consult with a tire professional or your vehicle manufacturer before making this switch.

How Much Taller Is a 285/75r17 Tire Than a 285/70r17?

A 285/75r17 tire is 1.12 inches (28.5 mm) taller than a 285/70r17 tire. The 285/75r17 has an overall diameter of 33.83 inches (859.3 mm), while the 285/70r17 has a diameter of 32.71 inches (830.8 mm).

This height difference represents a 3.3% increase in overall diameter for the 285/75r17 compared to the 285/70r17.

Our Observation

Switching from 285/75R17 to 285/70R17 tires offers a mix of benefits and drawbacks. The smaller size can provide a sportier look and potentially sharper handling on-road.

However, it comes at the cost of slightly reduced ground clearance and potentially less cushioning over rough terrain. For most daily driving scenarios, both on and off-road, the differences will be subtle.

The impact on fuel economy and speedometer accuracy, while present, is likely to be negligible in real-world conditions.

Ultimately, the decision to switch should be based on your specific driving needs and preferences, keeping in mind that the size difference slightly exceeds the recommended 3% threshold.

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Asma Akter

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.