265/70r17 vs 245/75r17 Tire: What’s the Difference?

There are several varieties of tires, and they have advanced significantly in terms of design, types, and sizes. Replacing tires might be perplexing if you are unfamiliar with the correct specifications.

As a result, our focus today will be on whether or not the 265/70r17 and 245/75r17 tires are interchangeable. We will discuss everything you need to know regarding the differences between 265/70r17 and 245/75r17 tires.

265/70r17 vs 245/75r17 Tire: Comparison Table

Between 265/70r17 and 245/75r17, there is a 5% aspect ratio difference. This difference will affect the overall parameters, as we will see in the comparison table below.

265/70r17 TireType245/75r17 Tire
31.61 inches or 802.8 mmDiameter difference -0.14 (-3.5) -0.4% inches (mm)31.47 inches or 799.3 mm
10.43 inches 265 mmWidth difference -0.79 (-20) -7.5% inches (mm)9.65 inches 245 mm
99.29 inches or 2522.07 mmCircumference difference -0.43 (-11) -0.4% inches (mm)98.86 inches or 2511.08 mm
7.3 inches or 185.5 mmSidewall Height difference -0.07 (-1.75) -0.9% inches (mm)7.23 inches or 183.75 mm
638.1 RPM or 396.5 KMRevolutions per mile difference 2.79 (1.74) 0.4% (km)640.9 RPM or 398.24 KM

The first and foremost difference between 265/70r17 and 245/75r17 tires is the difference in width, and it is massive. Observing the chart, we can see that the width change is 7.5%. So interchanging between tires can create some road traction and resistance problems.

In terms of diameter and circumference, these two tires have very little change, which is only about -0.4%, which is great for changing tires. Even the sidewall length difference between 265/70 r17 and 245/75r17 is significantly less, which is only -0.9%.

Lastly, a 265/70r17 tire is bigger than a 245/75r17 tire. The 265/70r15 will generate fewer revolutions per mile as a consequence of its size; as seen in the table above, the difference in revolutions is about 0.4 percent.

How to read the tire sizes 265/70r17 and 245/75r17?

There are four parts to the tire size 265/70 r17, and each part bears a certain meaning. Before you decide to interchange or replace the tires, you must learn about them. Here is the explanation of each part of the tire size 265/70r17.

  • 265 means the width of the tires in millimeters
  • 70 shows the percentage of height to the width or the Aspect Ratio
  • R indicates Radial Construction
  • 17 indicates the Diameter of the Rim

Doing the Same for Tire Sizes 245/75r17

  • 245 means the width of the tires in millimeters
  • 75 shows the percentage of height to the width or the Aspect Ratio
  • R indicates Radial Construction
  • 17 indicates the Diameter of the Rim

What’s The Difference Between 265/70r17 and 245/75r17 Tire?

By now you’ve learned the basics of using two tires interchangeably, now let’s see implementing the theory in a real example. Below, we have compared 265/70r17 and 245/75r17 tires in terms of width, aspect ratio, construction materials, and rim diameter. 

Width

If you measure from one sidewall to the other sidewall of a tire, you will get the width. It is expressed in millimeters. You can instantly learn the Width of a tire just by looking at the tire size index.

The first three digits of a tire size index indicate the Width of that tire. As you can see, the first three digits of 265/70r17 are 265. It means the width of that tire is 265 millimeters. 

Likewise, the three-digit number of 245/75r17 is 245. It means the Width of that tire is 245 millimeters. So the difference in the Width is 245 – 265 = -20 millimeters.

Now, if you switch to the tire size which is 0 millimeters more or less in Width, it shouldn’t be a problem. 

But you cannot switch tire size depending on Width only. You must consider the Sidewall Height as well. The Sidewall Height depends on Width and Aspect Ratio.

Aspect Ratio

As you can see, there’s a difference between the Aspect Ratio of the two tire sizes. The aspect ratio of 265/70r17 is 70, whereas the aspect ratio of 245/75r17 is 75.

So to check the interchangeability of these tires, our sole concern is to analyze how the differences in the aspect ratio impact the other measurements. Let’s start with the simple question first: what is the Aspect Ratio? And its relation with other measurements.

Aspect Ratio is the ratio of the sidewall from wheel to tread and the width. This measurement is usually represented in a percentage. 

In our example, 265/70r17 Tire size has a width of 265 with an aspect ratio of 70%. So the sidewall height will be 265 x 0.70 or 7.3 inches or 185.5 mm. You can get the number by simply putting the value on the equation.

Equation: Height of a Sidewall = Aspect Ratio of Tire x Width.

On the other hand, the Sidewall Height of 245/75r17 is 7.2 inches. Though the Aspect Ratio of the two tire sizes is different, they have almost a similar sidewall height.

Hence 265/70 is wider but interchangeable with 245/75.

Construction Type

The tire size index informs you about the Construction Type of a tire. It is expressed by a letter in the tire size index. 

Both 265/70 r17 and 245/75r17 have the same letter ‘R’. So, both the tires have Radial Construction in terms of construction type.

Such tires have a sophisticated construction with square footprints on the top. The Radial tires are ideal for driving on-road. 

They are resistant to heat and water. They are next-gen tires and can provide great fuel efficiency.  

Another famous construction type is Bias Ply. They are also known as Cross-ply. It is expressed by the letter ‘B’ in a tire size index. This type is great for driving off-road.

Rim Diameter

To know which tire size fits your vehicle, you must know the wheel rim size of your vehicle as well as the Rim Diameter of a tire. 

For instance, if your vehicle has a 16-inch wheel rim, you can use the tire which has a 16-inch Rim Diameter.

By looking at a tire size index, you can learn instantly the Rim Diameter of a tire. The last two digits of a tire size index indicate the Rim Diameter. It is measured in inches.

As you can see, the Rim Diameter of 265/70r17 is 17 inches. Similarly, the Rim Diameter of 245/75r17 is 17 inches.

It means that if your vehicle has a 17-inch wheel rim, you can use both tire sizes. But make sure to use the same size tires for all the wheels.

Can You Interchange Between 265/70r17 vs 245/75r17 tire

Yes, because the diameter difference is only 0.4 percent, it meets the criterion for tire interchange because the diameter difference is less than 3%.

You must, however, satisfy specific requirements. The two tires on the same axle must be on the exact tire. It implies you’ll be purchasing at least a couple of the 265 tires.

Speedometer Difference: Using the current Tire Size 265/70r17 Instead Of the New Tire Size 245/75r17

Look at the Table. It shows differences in speedometer reading and the actual speed at any given time when the current Tire Size is 265/70 r17 instead of 245/75r17. 

Speedo ReadingActual Speed
20 mph (32.19 km/h)19.91 mph (32.05 km/h)
25 mph (40.23 km/h)24.89 mph (40.06 km/h)
30 mph (48.28 km/h)29.87 mph (48.07 km/h)
35 mph (56.33 km/h)34.85 mph (56.08 km/h)
40 mph (64.37 km/h)39.83 mph (64.09 km/h)
45 mph (72.42 km/h)44.8 mph (72.1 km/h)

Speedometer Difference: Using current Tire Size 245/75r17 Instead Of New Tire Size 265/70r17

The table shows the differences in speedometer reading and the actual speed at any given time when the current Tire Size is 245/75r17 instead of 265/70r17.

Speedo ReadingActual Speed
20 mph (32.19 km/h)20.09 mph (32.33 km/h)
25 mph (40.23 km/h)25.11 mph (40.41 km/h)
30 mph (48.28 km/h)30.13 mph (48.49 km/h)
35 mph (56.33 km/h)35.15 mph (56.57 km/h)
40 mph (64.37 km/h)40.18 mph (64.66 km/h)
45 mph (72.42 km/h)40.18 mph (64.66 km/h)

What you must consider Before Interchange or Replace Tire? 

There are important things to consider before replacing or swiping the Tires. You cannot simply replace the 265/70r17 tire with the 245/75r17 tire that is in a different shape.

For example, if the aspect ratio of the existing tire is 40%, replacing it with a tire that has an aspect ratio of  45% might not be a good option.

Doing so will have various consequences on the car’s overall performance, such as variations in top speed and speedometer.

However, to a certain extent, such as minor changes in the diameter or the sidewall, you can switch Tires. However, this can only be done in compliance with the manufacturers’ recommendations.

Anyway, when replacing the Tire, the simple guideline to follow is that the current tire’s size, load index, and speed rating should all match with the replacement Tire.

Load Index and Speed Index of a Tire 265/70r17 and 245/75r17

The load index refers to the maximum load-bearing capacity, whereas the speed index refers to the Tire’s maximum allowable speed at a full load. These are very crucial stats to know before you decide to interchange tires.

Index information can be found on the sidewall right after the Tire size number. It is a combination of numbers and letters that bear a particular meaning. 

Here is an example of how the index information is usually written on the sidewall: 265/70 r17 90A. The 90A stands for load and speed index, with 90 indicating a maximum load-bearing capacity of 600 kg, whereas ‘A’ denotes an allowed speed of up to 170 km/h.

Check the load and speed index. They must be as close as possible to fit precisely. These values change depending on the vehicle’s weight and wheel size. Here is a table that shows various load and speed indexes, so you get the idea.

Load IndexKgSpeed IndexSpeed Limit
65290QUp to 160 Km/h
66300RUp to 170 Km/h
67307SUp to 180 Km/h
68315TUp to 190 Km/h
69325HUp to 210 Km/h

Size of the Tire 

The size of the Tire is another vital piece of information to know to exchange the tires properly. The large number on the sidewall shows the tire size.

For example, the marking 265/70r17 on the sidewall represents the size of the Tire. You can also find it in the user manual, on the sidewall, and in other places such as inside the fuel flap or glove compartment.

What Size Tires Is 265/70r17 in Inches?

265/70 r17 tires have a 31.6″ diameter, 10.4″ section width, and 17″ wheel diameter.

The circumference is 99.2″ and they make 638 revolutions per mile. The Sidewall Height of this Tire is 7.3 inches.

What Size Tires Is 245/75r17 in Inches?

245/75r17 tires have a diameter of 31.5″, a section width of 9.6″, and a wheel diameter of 17″. 

The circumference is 98.8″ and they have 641 revolutions per mile. The Sidewall Height of this Tire is 7.2 inches.

Conclusion

To summarize, there are several tire kinds. Since there are so many tires, vehicle drivers may not be aware of all of them, so knowing a few is crucial. As a result, today, we discussed whether 265/70r17 and 245/75r17 tires are interchangeable.

Simply said, these tires are interchangeable, and you will have no trouble substituting one for the other.

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