285/65r20 vs 285/60r20 Tire: What’s the Difference?

Suppose you’re going to change your vehicle’s 285/65r20 tires after thousands of miles of driving. Now you can’t find 285/65r20 and many shops are suggesting 285/60r20. In this case, would it be a good idea?

If you ask us, we’d always suggest avoiding such interchanging. The main problem here is the difference in diameter, which is nearly 3.2%. Now, the comparison of 285/65r20 vs 285/60r20 tires, can tell the possible result.

Therefore, we’ve thought of showing you the major differences between the two mentioned types to help decide on whether both of them are interchangeable or not.

285/65r20 vs 285/60r20 Tire: Comparison Table

Here’s our chart showing the differences side by side in perfect numbers.

285/65r20 TireType285/60r20 Tire
34.59 inches or 878.5 mmDiameter difference -1.12 inches (-28.5mm) -3.2% inches (mm)33.46 inches or 850 mm
11.22 inches or 285 mmWidth difference 0 (0) 0% inches (mm)11.22 inches or 285mm
108.66 inches or 2759.89 mmCircumference difference -3.53 inches (-89.54mm) -3.2% inches (mm)105.13 inches or 2670.35 mm
7.29 inches or 185.25 mmSidewall Height difference -0.56 inches (-14.25mm) -7.7% inches (mm)6.73 inches or 171 mm
583.12 RPM or 362.33 KMRevolutions per mile difference 19.55 (12.15) 3.4% (km)602.67 RPM or 374.48 KM

Let’s break the ice and describe the whole comparison table. 

First of all, 285/60r20 is 1.12 inches smaller than 285/65r20. We know that if the tire is at least 3% smaller than the recommended model, it’s risky to use that tire. Installing new 285/60 tires in cars might lead to anti-lock brake malfunction. 

It is a very serious issue that has been identified as the reason behind several accidents. But you can overcome the problem by changing the old brackets and shocks.

The other noticeable things in 285/65r20 vs 285/60r20 are that 285/60 has a smaller sidewall and circumference. 

Together, they make the model a low-profile tire construction. Low-key tires can improve car speed along with driving experience. Honestly speaking, these are the biggest plus points apart from a bigger problem we’ve mentioned earlier.

How to read the tire sizes 285/65r20 and 285/60r20?

There are four parts to the tire size 285/65r20, 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 285/65r20.

  • 285 indicates the width of the tires in millimeters
  • 65 indicates the percentage height in relation to the width or the Aspect Ratio
  • R indicates Radial Construction
  • 20 indicates the Diameter of the Rim

Doing the Same for Tire Sizes 285/60r20

  • 285 indicates the width of the tires in millimeters
  • 60 indicates the percentage height in relation to the width or the Aspect Ratio
  • R indicates Radial Construction
  • 20 indicates the Diameter of the Rim

What’s The Difference Between 285/65r20 and 285/60r20 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 285/65r20 and 285/60r20 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 285/65r20 are 285. It means the width of that tire is 285 millimeters.

Likewise, the three-digit number of 285/60r20 is 285. It means the Width of that tire is 285 millimeters. So the difference in the Width is 285 – 285 = 0 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, the only difference between the two Tire sizes is the aspect ratio. The aspect ratio of 285/65r20 is 65, whereas the aspect ratio of 285/60r20 is 60. On the other hand, the Width and the Rim diameter of the two tire sizes are identical.

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, 285/65r20 Tire size has a width of 285 with an aspect ratio of 65%. So the sidewall height will be 285 x 0.65 or 7.3 inches or 185.25 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.

Similarly, the Sidewall Height of 285/60r20 is 6.7 inches.

Though the Width of the two tire sizes is identical, there’s a gap between the sidewall heights because of the Aspect Ratio.

This change affects the value of diameter, circumference, and the total number of revolutions per mile.

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 285/65r20 and 285/60r20 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 285/65r20 is 20 inches. Similarly, the Rim Diameter of 285/60r20 is 20 inches.

It means that if your vehicle has a 20-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 285/65r20 and 285/60r20 Tire?

As the diameter difference is around 3%, interchanging is surely risky here. It should be strictly avoided for novice DIYers.

But if you have the budget to change stabilizing bars, brackets, and shocks, then 285/65r20 and 285/60r20 are interchangeable. It’s a good deal to have 285/60 types installed for getting better performance. But don’t ever think of only changing high profile tires with low profile tires without buying new accessories around wheels.

Speedometer Difference: Using the current Tire Size 285/65r20 Instead Of the New Tire Size 285/60r20

Look at the Table. It shows differences in speedometer reading and the actual speed at any given time when the current Tire Size is 285/65r20 instead of 285/60r20. 

Speedo ReadingActual Speed
20 mph (32.19 km/h)19.35 mph (31.14 km/h)
25 mph (40.23 km/h)24.19 mph (38.93 km/h)
30 mph (48.28 km/h)29.03 mph (46.71 km/h)
35 mph (56.33 km/h)33.86 mph (54.5 km/h)
40 mph (64.37 km/h)38.7 mph (62.29 km/h)
45 mph (72.42 km/h)43.54 mph (70.07 km/h)

Speedometer Difference: Using current Tire Size 285/60r20 Instead Of New Tire Size 285/65r20

The table shows the differences in speedometer reading and the actual speed at any given time when the current Tire Size is 285/60r20 Instead Of 285/65r20.

Speedo ReadingActual Speed
20 mph (32.19 km/h)20.67 mph (33.27 km/h)
25 mph (40.23 km/h)25.84 mph (41.58 km/h)
30 mph (48.28 km/h)31.01 mph (49.9 km/h)
35 mph (56.33 km/h)36.17 mph (58.22 km/h)
40 mph (64.37 km/h)41.34 mph (66.53 km/h)
45 mph (72.42 km/h)46.51 mph (74.85 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 285/65r20 tire with the 285/60r20 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 a variety of 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 285/65r20 and 285/60r20

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. 

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 285/65r20 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 285/65r20 in Inches?

285/65r20 tires have a 34.6″ diameter, 11.2″ section width, and 20″ wheel diameter.

The circumference is 108.6,” and they make 583 revolutions per mile. The Sidewall Height of this Tire is 7.3 inches.

What Size Tires Is 285/60r20 in Inches?

285/60r20 tires have a diameter of 33.5″, a section width of 11.2″, and a wheel diameter of 20″. 

The circumference is 105.1,” and they have 603 revolutions per mile. The Sidewall Height of this Tire is 6.7 inches.

Summary

Everyone tries to modify four-wheelers to improve their performance. If you can also improve your car performance by adding new tires, then it’s a good thing. 

Today, we’ve learned about two different car models that are interchangeable with lots of risk factors. Often, people think of such modification with the mindset of changing several other types of equipment so that the whole vehicle can adapt to the change.

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