Tire Size 245/75r17 vs 255/75r17

The tire sizes 245/75R17 and 255/75R17 are very similar, with the only difference being the width. The 255/75R17 tire is 10mm wider than the 245/75R17 tire. This will result in a slightly larger tire diameter, leading to a slight increase in speedometer reading and fuel consumption.

245/75r17 vs 255/75r17 Table

This helpful comparison table offers an in-depth analysis of the disparities between tire sizes 245/75R17 and 255/75R17.

Diameter inches31.47 (799.3)32.06 (814.3)0.59 (15)
Width inches9.65 (245)10.04 (255)0.39 (10)
Circum. inches98.86 (2511.08)100.72 (2558.2)1.86 (47.12)
Sidewall Height7.23 (183.75)7.53 (191.25)0.3 (7.5)
Revolutions640.9 (398.24)629.09 (390.9)-11.81 (-7.34)

Overall Diameter
The overall diameter refers to the total height of the tire, measuring from the base to the top. The 245/75R17 has an overall diameter of 31.47 inches (799.3 mm), while the 255/75R17’s diameter is slightly larger at 32.06 inches (814.3 mm).

Although minor, this difference of 0.59 inches (15mm), a 1.9% increase, can impact ride comfort, speedometer accuracy, and fuel efficiency. A larger diameter, as in the case of 255/75R17, can improve ride comfort as the tire can absorb more shocks and bumps.

However, it can make the speedometer slightly inaccurate because the vehicle travels farther with each tire revolution than what the speedometer was calibrated for. A larger tire can also negatively affect fuel efficiency, as it requires more energy to rotate.

Section Width
Section width measures the tire’s width from one sidewall to the other. The 245/75R17 has a width of 9.65 inches (245mm), while the 255/75R17 tire is broader at 10.04 inches (255mm). This is a 4.1% increase or 0.39 inches (10mm) wider.

A wider tire, like the 255/75R17, can offer better traction and stability, especially in turns, due to the increased contact patch. But, it might also lead to increased rolling resistance, which could marginally lower fuel efficiency.

The circumference is the total distance around the tire. The 245/75R17 tire has a circumference of 98.86 inches (2511.08mm), while the 255/75R17 tire has a slightly larger circumference of 100.72 inches (2558.2mm), a 1.9% difference.

A larger circumference means the tire covers more ground per revolution, potentially making the vehicle slightly faster at the same engine RPM but negatively affecting acceleration.

Sidewall Height
Sidewall height refers to the measurement from the rim to the tread. The 245/75R17 tire has a sidewall height of 7.23 inches (183.75mm), while the 255/75R17 has a taller sidewall of 7.53 inches (191.25mm), which is a 4.1% increase.

The taller sidewall on the 255/75R17 can absorb more shocks from the road, making for a smoother ride. However, a larger sidewall could lead to a slight reduction in steering response and precision.

Revolutions Per Mile
Revolutions per mile refer to how many times a tire will rotate in one mile. The 245/75R17 has a higher number of revolutions per mile, 640.9, compared to 629.09 for the 255/75R17, a difference of -11.81 (-1.8%).

A tire with fewer revolutions per mile, like the 255/75R17, travels farther with each rotation. While this might improve top speed, it can decrease acceleration and slightly misalign the speedometer’s reading.

Wheel Size
Both the 245/75R17 and 255/75R17 are designed to be fitted onto a 17-inch wheel, and the ‘R’ in their descriptions signifies that they are both Radial type tires.

This means their cord plies are arranged at 90 degrees to the direction of travel, offering more flexible sidewalls, improved ride quality, and better fuel efficiency.

Alternative Tire Size of 255/75r17
The replacement tires should not exceed a 3% difference in overall diameter compared to the original tires.

Tire SizeOverall DiameterDifference
275/65R1731.1″ (790 mm)-2.9%
255/70R1731.1″ (790 mm)-2.9%
305/60R1731.4″ (798 mm)-2.0%
245/75R1731.5″ (800 mm)-1.7%
285/65R1731.6″ (802 mm)-1.5%
265/70R1731.7″ (804 mm)-1.2%
235/80R1731.8″ (808 mm)-0.7%
345/55R1732.0″ (812 mm)-0.2%
275/70R1732.2″ (818 mm)0.5%
305/65R1732.6″ (828 mm)1.7%
235/85R1732.8″ (832 mm)2.2%
285/70R1732.8″ (832 mm)2.2%

Alternative Tire Size of 245/75r17
Ensure that the replacement tires maintain an overall diameter that is within 3% of the original tires.

Tire SizeOverall DiameterDifference
235/75R1730.9″ (784 mm)-2%
275/65R1731.1″ (790 mm)-1.3%
255/70R1731.1″ (790 mm)-1.3%
305/60R1731.4″ (798 mm)-0.2%
285/65R1731.6″ (802 mm)0.2%
265/70R1731.7″ (804 mm)0.5%
235/80R1731.8″ (808 mm)1%
345/55R1732″ (812 mm)1.5%
255/75R1732″ (814 mm)1.8%
275/70R1732.2″ (818 mm)2.3%

Our Observation
Choosing between 245/75R17 and 255/75R17 largely depends on your driving conditions and priorities. If you value ride comfort and better traction, especially when cornering, the 255/75R17 tire’s larger diameter and width would be beneficial. However, the larger size could lead to slightly lower fuel efficiency and a less accurate speedometer reading.

On the other hand, the 245/75R17 tire would provide better fuel efficiency due to its smaller size and better speedometer accuracy. Although it might not offer as smooth a ride as the larger tire or the same level of traction, it would provide slightly better steering precision.

Remember, when considering changing tire sizes, always consult your vehicle’s manufacturer guidelines or a tire professional to ensure safety and compatibility with your vehicle.

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