What Is The Difference Between 285/70R17 and 285/75R17?

While car owners may know a lot of tire brands, they are unaware of the size of tires. As a result, they end up buying the wrong tire size for their vehicles. Knowing the tire size is very important for automotive enthusiasts, especially the ones with their own vehicles.

In case you don’t know, 285/70R17 and 285/75R17 are two common terms for defining the size of a tire. This combination of digits and letters is hard to understand. Therefore, it has become a common curiosity among many people. But the real curiosity lies in the difference between 285 70R17 and 285 75R17. 

If you really want to know the difference between these two tire sizes, then stick to the very end of this article.

What is Tire Size?

In a nutshell, the 285 75R17 is the newer version of the 285 70R17 tire size. So, there won’t be much difference between these two tire sizes. Before you go any further, we want your full attention here. You won’t fully understand the difference between 285 70R17 and 285 75R17 unless you know what this combination of numbers and letters really indicates. 

To give a clear idea about the tire size, we are going to give an example. Let’s consider your car has tire sizes indicating P 205/65 R15. This combination not only defines the tire size but also refers to other important facts. Here is the breakdown – 

  • P stands for – Type of the tire
  • 205 stands for – Tire width in meters
  • 65 stands for – The aspect ratio of height/width
  • R stands for – Radial construction of the tire (It can differ from other letters i.e. B)
  • 15 stands for – Rim diameter in inches

(Image Credit: bmw of stratham)

Now that you have understood what the combination for tire size defines, it won’t be hard for you to understand the difference between 285 70R17 and 285 75R17. Still, we will break down the comparison into 4 parts to represent the difference in an insightful way. 

285/70R17 Vs 285/75R17 Tire: Whats The Difference?

Width

Judging by the first digits of both tire size indicators, we are confirmed that there is no difference in the width of these two tire sizes. Both tires are 285 meters wide. These digits are measured directly by the tire manufacturers. 

So if you are wondering particularly about the width, then taking any of the 285 70R17 or 285 75R17 will suit your vehicle. However, don’t buy directly only relying on this fact. We are about to discuss more that you need to know.   

Aspect Ratio

Okay, there is a big difference between 285 70R17 and 285 75R17 in terms of aspect ratio. As you can see, one tire has an aspect ratio of 70 and another has 75. There is a difference of 5 between the aspect ratios of these two tires. 

See! You are acknowledging the distinction of 285 70R17 or 285 75R17 eventually. The aspect ratio indicates the height of the tire’s cross-section to its width and it has a major impact on the compatibility of vehicles. Even if the width is the same for both tires, you can’t expect to attach any one of them without considering the aspect ratio.       

Radial Construction

Another significant factor of tire size indicator is the radial construction. Considering both 285 70R17 and 285 75R17, the radial construction is the same as both tires have the ‘R’ letter on the sidewall. 

If you don’t know what radial construction means, then don’t worry; we will enlighten you. The radial construction defines how the tire was assembled and the handling characteristics of the tire. Judging by the ‘R’ letter, one can find out that both 285 70R17 and 285 75R17 are radial type tires. 

This doesn’t always mean there will be an ‘R’ letter on the sides of all tires. There can be other letters like ‘B’. Here is how the letters define the characteristics of a tire –

  • R – Indicates the tire is a radial type
  • B – Indicates the tire is a bias ply type       

Rim Diameter

The rim diameter is the width of the opening in the tire where it would be mounted on a wheel. It is measured from one heel through the opening to the other side of the same heel. Generally, the rim diameter is measured in inches. 

Judging by both tire size indicators 285/70R17 and 285/75R17, you can easily guess there is no difference in the rim diameters of the tires. We assume any one of these tires will adjust wheels that have a diameter of 17 inches.    

Wrapping Up With A Comparison Table – Tire Size 285/70R17 vs 285/75R17   

If you have read this far, you may have understood there really isn’t much difference between 285/70R17 and 285/75R17 tire sizes except for the aspect ratio. To sum up, we have included a comparison table of 285/70R17 vs 285/75R17 so that you can have a quick overview. 

Parameter285 70R17285 75R17Difference
Section width285 mm285 mm0 mm (0%)
Overall diameter831 mm859 mm+29 mm (+3%)
Circumference2610 mm2700 mm+90 mm (+3%)
Revs per km383370-13 (-3%)
Sidewall height200 mm214 mm+14 mm (+7%)
Aspect Ratio7075+5 (+3.5%)

To compare the sides and fronts of 285/70R17 and 285/75R17, take a look at these two pictures – 

Relevant Questions

What is the speed rating of a tire?

Ans: Speed rating is basically a number that indicates the maximum speed at which a tire will work well. Although speed ratings are specified for passenger cars, there are no speed ratings for light truck tires.

Below, the chart shows various tire ratings corresponding to their maximum speeds – 

RatingMaximum speed
Q99 mph
S112 mph
T118 mph
U124 mph
H130 mph
V149 mph
W168 mph
Y186 mph
Z> 149 mph

How to find the specifications of a tire?

Ans: Finding the specifications of a tire is easy if you have a little knowledge of tires. Usually, the side of a tire that is revealed outwards is called a sidewall. And all the necessary information of a tire is molded into its sidewall. While some information is easy to understand just by looking, some require a little knowledge to decode. Hopefully, the following figure will help you to understand what we are talking about – 

How to easily calculate the aspect ratio of a tire?

Ans: Aside from dividing the tire height by its width, you can easily calculate the aspect ratio of the tire. We will show you a trick for calculating the aspect ratio within an instant. You need to multiply the first digit by the second digit’s decimal form. 

As an example, we are going to consider 285 70R17. Here the first number is 285 and the decimal form of the second number will be 0.70. If we multiply these two numbers, then it will be 285 x 0.70 = 199.5; which is the aspect ratio of the tire. 

Final Words 

We hope you are fully aware of the difference between 285 70R17 and 285 75R17 after reading this article. Alongside this, we think we have taught you some useful definitions that are related to tire size. Now you are one step ahead of choosing the right tire for your vehicle.

Remember, the difference is a difference no matter how small or big it is. For safe driving, minor differences in the tire size can make a significant impact. 

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