Tire Size 305/70r17 vs 285/70r17
The main difference between 305/70Rr17 and 285/70r17 tires is their section width. 305/70r17 tires are 20mm wider than 285/70r17 tires. This difference in width can significantly impact the performance and handling of your vehicle.
| / | R |
| / | R |
| Parameter | 235/35 R18 | 205/40 R18 | Differ. |
|---|---|---|---|
| Tire Height | |||
| Section Width | |||
| Circumference | |||
| Sidewall Height | |||
| Revolutions | |||
| Rim Size |
Fitment Guide
Replacement tires should generally be within 3% of the original tire’s overall diameter to avoid clearance issues or speedometer inaccuracies.
The overall diameter of 305/70R17 tires is 3.3% larger than 285/70R17 tires. So 285/70R17 tires would be a direct replacement, while 305/70R17 tires might require adaptations like a lift kit to accommodate the larger size.
Ground Clearance
The 305/70R17 tire size provides 0.55 inches (14mm) more ground clearance than the 285/70R17 size due to its taller sidewall profile.
This added clearance is useful for off-road driving, helping prevent scrapes and damage from obstacles. However, the larger 305/70R17 diameter also causes a lower speedometer reading than the 285/70R17.
Gas Mileage
The wider 305/70R17 tires have more rolling resistance and rotational mass compared to 285/70R17 tires.
This generally leads to slightly worse fuel efficiency with the 305 widths. So, the narrower 285/70R17 is a better choice for optimal gas mileage.
Ride Comfort
The taller sidewall and wider tread of 305/70R17 tires provide more cushioning and the ability to absorb impacts from rough roads.
This can contribute to a more comfortable ride, especially over uneven terrain. The lower profile 285/70R17 transmits more road noise and vibration into the cabin.
Aesthetics
Subjectively, the taller sidewall of the 305/70R17 gives a more aggressive, robust look compared to the lower profile 285/70R17.
This stretched aesthetic suits trucks and SUVs well. However, the 285 width is more aerodynamic.
Handling & Stability
The shorter sidewall and narrower width of the 285/70R17 tire provide sharper, more responsive handling on paved roads.
The 305/70R17’s taller sidewall flexes more, reducing handling precision slightly. Both offer stable performance, but the 285 width has a handling advantage.
Noise & Vibration
The extra cushioning of the 305/70R17 helps absorb road noise and vibrations, leading to a slightly quieter, smoother ride.
The stiffer 285/70R17 sidewall transmits more noise and vibration into the cabin over bumps. However, both tires perform well in this regard.
Durability & Wear
The wider 305/70R17 tread contacts the road with more surface area, distributing wear more evenly across the tire.
This can potentially increase tread life. However, the added weight of 305-width tires also puts more strain on suspension components.
Adverse Conditions
The 285/70R17 tires’ narrower profile allows them to cut through snow more efficiently.
But, the taller 305/70R17 sidewall provides more flexible traction on loose surfaces like mud or sand. Performance in rain, snow, and off-road is comparable.
Speedometer Difference
The larger diameter 305/70R17 tires will register a lower speedometer reading than the 285/70R17s at a given speed.
For example, at an actual speed of 20 mph, the speedometer reads 19.35 mph with 305/70R17 tires fitted.
Can I use 285/70r17 instead of 305/70r17?
No, it is not advisable to use 285/70r17 instead of 305/70r17. The diameter difference is -1.1 inches (-3.3%), exceeding the recommended 3% limit. This variance may affect vehicle performance and the accuracy of speedometer readings.
285/70r17 vs 305/70r17
This comparison table will help you understand the differences between 285/70r17 and 305/70r17 tire sizes.
How Much Taller Is A 305/70r17 Tire Than A 285/70r17?
The 305/70r17 tire is 1.1 inches (28 mm) taller than the 285/70r17 tire, representing a 3.3% increase in diameter.
The height of a 305/70r17 tire is 33.81 inches (858.8 mm), and a 285/70r17 tire has a height of 32.71 inches (830.60 mm).
How Much Wider Is A 305/70r17 Tire Than A 285/70r17?
The 305/70r17 tire is 0.79 inches (20 mm) wider than the 285/70r17 tire, indicating a 6.6% increase in width.
Specifically, the 305/70R17 measures 12.01 inches (305mm) in width, while the 285/70R17 is narrower at 11.22 inches (285mm).
What Does 305/70r17 Mean?
The tire size 305/70R17 denotes a tire that is 305 millimeters wide, with a 70% aspect ratio (height to width), radial construction (denoted by “R”), and designed for a 17-inch wheel. The equivalent measurement in inches for the tire size 305/70R17 is 33.9x12R17.
What Does 285/70r17 Mean?
The tire size 285/70R17 specifies a tire that is 285 millimeters wide with a 70% aspect ratio. The tire has a radial construction, indicated by the “R,” and is designed to fit on a 17-inch wheel. The tire dimensions 285/70R17 can be expressed as 32.8×11.2R17 in inches.
What Size Rim For 285/70r17?
The tire size 285/70r17 can be mounted on a 17-inch wheel. For a 285/70R17 tire, the recommended rim width ranges from 7.5 to 9.0 inches.
What Size Rim For 305/70r17?
The tire size 305/70R17 can be accommodated on a 17-inch wheel. To ensure the optimal fit, it is recommended to use a rim with a width between 8.0 and 9.5 inches.
Our Observation
Based on the differences analyzed, the 285/70R17 tire size seems better suited for on-road use, providing enhanced handling, efficiency, and a smoother ride on paved surfaces.
Meanwhile, the 305/70R17 size offers excellent off-road capability and a more comfortable ride over rough terrain thanks to its taller sidewall and wider tread.
Ultimately, we recommend the 285/70R17 tire for drivers who spend most of their time on highways and city streets.
For off-road adventurers or those needing maximum ground clearance, the 305/70R17 is a better choice. Select the tire that aligns with your vehicle’s main usage.
Meet Caitlin McCormack, a Tire Size Expert and Blogger Passionate About Everything Related to Tires. With Years of Experience in the Tire Industry, Caitlin Has Become an Expert in Tire Sizes and Their Impact on Vehicle Performance.
