Tire Size 275/65R18 vs 275/70R18

Choosing the right tire size for your vehicle is a crucial decision that affects not only the aesthetics and performance but also the overall safety and efficiency.

In this article, we will compare the 275/65r18 and 275/70r18 tire sizes, focusing on the benefits and shortcomings of switching from one size to the other.

Main Difference

The primary difference between the 275/65r18 and 275/70r18 tire sizes lies in their diameter and sidewall height.

The 275/70r18 has a larger diameter (33.16 inches) compared to the 275/65r18 (32.07 inches), resulting in a 3.3% difference.

This increased diameter translates to a higher sidewall height for the 275/70r18 (7.58 inches) versus the 275/65r18 (7.04 inches), affecting various aspects of the vehicle’s performance and characteristics.

Fitment Guide

When considering a switch between these two tire sizes, fitment is crucial. Replacement tires should be within 3% of the original tire’s overall diameter.

The 275/70r18 exceeds this threshold slightly at 3.3%, potentially requiring adaptations such as leveling or lift kits to prevent issues like rubbing.

On the other hand, the 275/65r18 fits well within the acceptable range, ensuring minimal adjustments are needed.

Ground Clearance

Switching from 275/65r18 to 275/70r18 increases ground clearance due to the larger diameter. This is beneficial for off-road driving and navigating rough terrain, as it reduces the risk of scraping the undercarriage.

Conversely, moving from 275/70r18 to 275/65r18 decreases ground clearance, which can make the vehicle more susceptible to damage on obstacles and rough roads but might improve aerodynamics and fuel efficiency.

Gas Mileage

The 275/65r18, with its smaller diameter, generally offers better fuel efficiency. This is due to a smaller contact patch and less rotational mass, which reduces rolling resistance.

In contrast, the 275/70r18, being larger, has increased rolling resistance and rotational mass, potentially detracting from fuel efficiency. For daily commuters and long-distance travelers, the 275/65r18 could be the more economical choice.

Aesthetics Look

Aesthetics play a significant role in tire selection. The 275/70r18, with its larger size, provides a more aggressive and rugged appearance, which many off-road enthusiasts find appealing.

However, this larger size can hinder aerodynamic efficiency. The 275/65r18, while less aggressive in appearance, enhances aerodynamics, contributing to better overall vehicle performance.

Ride Comfort

Larger tires like the 275/70r18 offer better off-road performance due to increased sidewall height, which provides superior impact absorption.

This results in a more comfortable ride on rough terrains. On the other hand, the 275/65r18, with its smaller size, tends to perform better on highways and city streets, offering a smoother ride on paved surfaces.

Speedometer Accuracy

Switching to a different tire size affects speedometer and odometer readings. The 275/70r18, being larger, will cause the speedometer to read slower than the actual speed.

For example, at a speedometer reading of 20 mph, the actual speed would be 19.35 mph. Conversely, the 275/65r18, being smaller, will make the speedometer read faster than the actual speed.

This difference must be accounted for to maintain accurate speed and distance measurements.

Handling and Stability

The 275/65r18 typically offers enhanced handling and quicker response on paved roads due to its smaller size. It provides better maneuverability and stability in urban and highway conditions.

In contrast, the 275/70r18, with its larger size, improves stability and traction, particularly in off-road scenarios or on uneven surfaces, making it ideal for adventurous driving.

Durability and Wear

Smaller tires like the 275/65r18 can exhibit even wear and potentially longer tread life due to less stress on vehicle components.

Larger tires, such as the 275/70r18, endure more impacts and stress, which might introduce more wear to vehicle components but offer greater durability in off-road conditions.

Adverse Performance

In adverse conditions, tire performance varies significantly. The 275/65r18, being narrower, can navigate snow and ice more effectively by cutting through to the road surface.

In contrast, the 275/70r18, with its larger and potentially wider contact patch, provides better traction in off-road or muddy conditions, making it a better choice for rugged environments.

Noise and Vibration

The 275/65r18 generally provides a quieter ride on smooth surfaces due to its smaller size and less aggressive tread patterns. However, it might transmit more vibrations from road irregularities.

The 275/70r18, especially with aggressive treads, might generate more road noise but can dampen vibrations better due to increased air volume and sidewall height, offering a more comfortable ride on rough terrains.

275/65R18 vs 275/70R18

This table compares the key features of tire sizes 275/65R18 and 275/70R18.

Feature	275/65R18	275/70R18	Difference
Diameter inches (mm)	32.07 (814.7)	33.16 (842.2)	1.08 (27.5) 3.4%
Width inches (mm)	10.83 (275)	10.83 (275)	0 (0) 0%
Circumference inches (mm)	100.77 (2559.46)	104.17 (2645.85)	3.4 (86.39) 3.4%
Sidewall Height inches (mm)	7.04 (178.75)	7.58 (192.5)	0.54 (13.75) 7.7%
Revolutions per mile (km)	628.78 (390.71)	608.25 (377.95)	-20.53 (-12.76) -3.3%
Speedo Reading	20 mph (32.19 km/h)	20.68 mph (33.27 km/h)	+0.68 mph

Difference Between 275/65R18 and 275/70R18

The main difference is the sidewall height; the 275/70R18 has a taller sidewall, resulting in a larger overall diameter compared to the 275/65R18.

Can I Use 275/70R18 Instead of 275/65R18?

Using 275/70R18 instead of 275/65R18 is generally not recommended due to the diameter difference exceeding 3%, which may affect handling and speedometer accuracy.

How Much Taller Is a 275/70R18 Tire Than a 275/65R18?

A 275/70R18 tire is approximately 1.08 inches taller than a 275/65R18 tire, impacting ground clearance and overall vehicle performance.

Our Observation

Switching from 275/65r18 to 275/70r18:

• Benefits: Increased ground clearance, better off-road performance, improved stability and traction, more aggressive aesthetics.
• Shortcomings: Slightly lower fuel efficiency, potential need for adaptations, less aerodynamic efficiency, speedometer inaccuracy.

Switching from 275/70r18 to 275/65r18:

• Benefits: Better fuel efficiency, improved aerodynamics, enhanced handling on paved roads, more accurate speedometer reading.
• Shortcomings: Reduced ground clearance, less aggressive appearance, potentially less stable in off-road conditions, higher susceptibility to damage on rough terrain.

Conclusion

Choosing between the 275/65r18 and 275/70r18 tire sizes depends on your driving needs and preferences. If you prioritize off-road capability, ground clearance, and a rugged appearance, the 275/70r18 is the better choice.

However, if you value fuel efficiency, handling on paved roads, and aerodynamic performance, the 275/65r18 is more suitable.

Ultimately, both tire sizes have their unique advantages and are tailored to different driving conditions. Consider your primary driving environment and personal preferences when making your decision to ensure optimal performance and satisfaction.