Tire Size 245/45r18 vs 235/50r18

The tire sizes 245/45R18 and 235/50R18 have some similarities but also some notable differences. The 245/45R18 tire has a wider width and a lower aspect ratio than the 235/50R18 tire.

This means that the 245/45R18 tire has a larger contact patch with the road, which can improve handling and braking performance. However, the 245/45R18 tire may also have a higher rolling resistance, which can reduce fuel economy.

245/45r18 vs 235/50r18 Table

For a comprehensive breakdown of the variations between 245/45R18 and 235/50R18 tire sizes, consult this beneficial comparison table.

Diameter inches27.25 (692.2)26.68 (677.7)-0.57 (-14.5)
Width inches9.25 (235)9.65 (245)0.39 (10)
Circum. inches85.61 (2174.61)83.82 (2129.06)-1.79 (-45.55)
Sidewall Height4.63 (117.5)4.34 (110.25)-0.29 (-7.25)
Revolutions740.06 (459.85)755.9 (469.69)15.83 (9.84)

Overall Diameter
The diameter is the distance across the tire, from one side to the other, passing through the center. The 235/50R18 has a diameter of 27.25 inches (or 692.2 mm), while the 245/45R18 tire has a slightly smaller diameter at 26.68 inches (or 677.7 mm).

This represents a 2.1% reduction, which may appear negligible, but could significantly impact performance. The larger diameter of the 235/50R18 tire can provide better ride quality because of the increased air volume. It also means the vehicle rides slightly higher, potentially improving ground clearance.

Section Width
Section width refers to the tire’s width from one sidewall to another. The 245/45R18 tire is 9.65 inches (or 245 mm) wide, compared to the 235/50R18 tire, which is 9.25 inches (or 235 mm) wide, showing an increase of 4.3%.

The wider 245/45R18 tire offers more contact with the road, leading to better traction, especially in corners and during maneuvers. However, this might result in a slight decrease in fuel efficiency due to increased rolling resistance.

Circumference refers to the distance around the outer edge of the tire. The 235/50R18 tire has a larger circumference (85.61 inches or 2174.61 mm) than the 245/45R18 tire (83.82 inches or 2129.06 mm), marking a difference of 2.1%.

A larger circumference can mean the tire covers more ground in one revolution, potentially offering better fuel efficiency but can result in less responsive handling.

Sidewall Height
Sidewall height, also known as tire profile or aspect ratio, is the height from the rim to the top of the tire. The 235/50R18 tire has a sidewall height of 4.63 inches (or 117.5 mm), while the 245/45R18 tire’s height is 4.34 inches (or 110.25 mm), a decrease of 6.2%.

A taller sidewall, like on the 235/50R18, often provides a smoother ride as it absorbs more road imperfections. Conversely, a shorter sidewall, like on the 245/45R18, can improve cornering stability and steering response.

Revolutions Per Mile
Revolutions per mile (or km) are the number of times a tire will revolve in one mile of travel. The 245/45R18 tire makes 755.9 revolutions per mile (or 469.69 per km), compared to the 235/50R18 tire’s 740.06 revolutions per mile (or 459.85 per km), a difference of 2.1%. More revolutions per mile can translate to more responsive acceleration and braking but can also increase wear on the tire.

Wheel Size
Both these tire sizes are designed for 18-inch wheels and are of the ‘R’ (radial) construction type, which means the internal ply cords are radial, i.e., arranged at 90 degrees to the direction of travel, providing increased strength and durability.

Alternative for 235/50r18
The overall diameter of the replacement tires must stay within 3% of the original tires’ measurement.

Tire SizeOverall DiameterDifference
135/80R1826.5″ (673 mm)-2.9%
215/50R1826.5″ (673 mm)-2.9%
155/70R1826.6″ (675 mm)-2.6%.5%
315/35R1826.7″ (677 mm)-2.3%
275/40R1826.7″ (677 mm)-2.3%
245/45R1826.7″ (677 mm)-2.3%
225/50R1826.9″ (683 mm)-1.4%
205/55R1826.9″ (683 mm)-1.4%
325/35R1827″ (685 mm)-1.2%
285/40R1827″ (685 mm)-1.2%
255/45R1827″ (687 mm)-0.9%
145/80R1827.1″ (689 mm)-0.6%
165/70R1827.1″ (689 mm)-0.6%
215/55R1827.3″ (693 mm)0%
295/40R1827.3″ (693 mm)0%
265/45R1827.4″ (695 mm)0.3%
345/35R1827.5″ (699 mm)0.9%
305/40R1827.6″ (701 mm)1.2%
245/50R1827.7″ (703 mm)1.4%
145/85R1827.7″ (703 mm)1.4%
205/60R1827.7″ (703 mm)1.4%
155/80R1827.8″ (705 mm)1.7%
225/55R1827.8″ (705 mm)1.7%
275/45R1827.8″ (705 mm)1.7%
315/40R1827.9″ (709 mm)2.3%
255/50R1828.1″ (713 mm)2.9%
285/45R1828.1″ (713 mm)2.9%

Alternative For 245/45r18
The overall diameter of the replacement tires should not exceed a 3% deviation from that of the original tires.

Tire SizeOverall DiameterDifference
285/35R1825.9″ (657 mm)-3%
225/45R1825.9″ (659 mm)-2.7%
335/30R1825.9″ (659 mm)-2.7%
185/55R1826″ (661 mm)-2.4%
145/70R1826″ (661 mm)-2.4%
255/40R1826″ (661 mm)-2.4%
205/50R1826.1″ (663 mm)-2.1%
295/35R1826.1″ (663 mm)-2.1%
345/30R1826.2″ (665 mm)-1.8%
265/40R1826.3″ (669 mm)-1.2%
235/45R1826.3″ (669 mm)-1.2%
305/35R1826.4″ (671 mm)-0.9%
135/80R1826.5″ (673 mm)-0.6%
215/50R1826.5″ (673 mm)-0.6%
155/70R1826.6″ (675 mm)-0.3%
275/40R1826.7″ (677 mm)0%
315/35R1826.7″ (677 mm)0%
205/55R1826.9″ (683 mm)0.9%
225/50R1826.9″ (683 mm)0.9%
285/40R1827″ (685 mm)1.2%
325/35R1827″ (685 mm)1.2%
255/45R1827″ (687 mm)1.5%
145/80R1827.1″ (689 mm)1.8%
165/70R1827.1″ (689 mm)1.8%
215/55R1827.3″ (693 mm)2.4%
295/40R1827.3″ (693 mm)2.4%
235/50R1827.3″ (693 mm)2.4%
265/45R1827.4″ (695 mm)2.7%

Our Observation
When comparing these tire sizes, it’s evident that the choice largely depends on personal preference and driving conditions. The 235/50R18 tire, with its larger diameter and taller sidewall, could be a better option for those seeking a smoother ride and slightly increased ground clearance.

Meanwhile, the 245/45R18 tire’s wider section width and higher revolutions per mile might be preferred by drivers who prioritize responsive handling, cornering stability, and precise control. However, the wider tire may decrease fuel efficiency slightly due to increased rolling resistance.

Both sizes have their merits. Before deciding, one should consider their driving style, usual driving conditions, and vehicle compatibility. Always consult a tire professional to ensure your vehicle’s selected tire size is safe and appropriate.

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