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How To Choose A Wheel Size?


In developing each car model, the designers determine the diameter of the disk, which is optimal for driving characteristics, as well as the width and height of the tires. However, there are many car owners who want to change the factory wheels to other, larger ones. The main reason for this decision is most often the desire to improve handling, increase cross-country ability and give the car a more spectacular appearance. How to choose the size of the wheels so that their replacement is beneficial, not harmful? We will tell you what you need to consider when installing disks of a larger diameter.

What is the danger of choosing the wrong size wheels?

The wheels and tires provided by the factory correspond to the rest of the technical parameters of the car. Installing wheels other than those recommended by the manufacturer may adversely affect the ride quality of the machine.

Cons of installing large drives

An attempt to replace the “native” disks with larger diameters and, consequently, weight, will lead to an increase in the unsprung weight of the car. The load on the engine increases, fuel consumption increases, and dynamics worsens. The suspension has a negative impact: its resource is not unlimited and is designed for the load that is created by standard wheels.

  • As a rule, a disc with a larger diameter is wider and protrudes further beyond the body, since it has a different seating depth in the wheel arch. Because of this, the load on the wheel bearings increases, and their service life is significantly reduced, by about 20-30%. In some cases, bearings require replacement every few thousand kilometers.

Disadvantages of Fitting Big Tires

More size means more weight. This applies not only to disks, but also to tires: with an increase in tire diameter, the mass of the wheel assembly increases, and hence the total unsprung mass.

In general, replacing standard wheels with new ones is a very expensive undertaking in terms of finances. You will have to spend money not only on a set of wheels and rubber for them. But also on tire fitting, and also be ready to repair tires more often due to their greater susceptibility to punctures.

How to choose the right combination of rims and tires?

We figured out the requirements that disks must meet. Let’s talk about which tires are best suited to make the ride comfortable and safe. From what protectors are installed on the car, its controllability, maneuverability, and ability to overcome various obstacles largely depend.

The simplest solution would be to choose a wheel assembly. For inexperienced car owners, this will ensure that the tire is fully consistent with the characteristics of the disk. Another plus is the balance passed by the wheel and full readiness for operation.

Choosing right tires

If you decide to choose tires yourself, it is important to consider several points.

  1. The inner (landing) diameter of the tire must match the diameter of the disk: if R14 is marked on it, 14-inch tires are bought.
  2. We pay attention to the permitted load index and the permissible speed index. Their recommended values ​​are indicated in the car’s operating manual. Deviation from the set parameters may adversely affect the driving performance of the car.
  3. Be sure to take into account the ratio of the width of the rim of the disc and the profile of the tire. To achieve a perfect tire fit, the first indicator should be equal to 70-75% of the second. We pay special attention to the fact that wheel manufacturers indicate the width of the rim in inches, and on tires. The same size is indicated in millimeters. To bring to a single measurement option, we use a special formula. Suppose you decide to choose tires 195/70 R15. We divide 195 mm by a factor of 25.4, and we get the width in inches -7.68, which we reduce by 30%. The final result of 5.38 is rounded up to the standard value that is closest to it – 5.5. This means that you should choose a wheel with 20-inch rims.

How to choose the right disk size?

Each rim is marked: combinations of letters and numbers pressed on it contain its exhaustive characteristics in several parameters. Let’s consider each of them in more detail.

1) Warning icons on the dashboard: “Check Engine” indicator

The “Check Engine” icon on the dashboard is the most common problem for cars and trucks. This indicator on the tidy lights up when the ECU (electronic engine control unit) detects an error code in the system in the operation of any system. In total, there are more than 200 possible error codes, in order to identify the cause. You need to do full-fledged electronic diagnostics at the car service nearest to you (most often it’s free).

2) High fuel consumption

When an engine is running normally, it burns fuel at a rate that helps fuel efficiency (fuel economy). However, some parts of the fuel system, such as fuel filters, air filters, mass air flow sensors, and oxygen sensors (Lamba probe), become dirty and wear out over time. If they are not replaced (and this is the most common cause of increased fuel consumption), this will cause the engine to use more fuel than usual.

3) Screeching brakes

Brakes in a car are sacred. It is on them that the safety of our car, and sometimes life, often depends! Therefore, when you notice any signs of problems, such as squealing or creaking, or if. For example, if the brake pedal becomes soft, you should of course take the car to an auto mechanic as soon as possible. Most often, a creak or screech indicates that it is necessary to replace the brake pads or brake discs.

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