Meaning and Code of Car Wheel Size

The size of car rims is a calculation that can be used as a reference when choosing rims and suitable cars. The size must be right or appropriate so that the newly purchased car rims can support the car's performance. 

To find out the size of the rim, it can be seen from the code consisting of numbers and letters found on the edge of the car rim. This code is sequential and has its own meaning. 

For example, a car rim with the code 7Jx16H2 ET49. The meaning of this code describes the width of the rim, flange distance, rim diameter, hump model, PCD (Pitch Circle Diameter), and the rim's offset. To clarify, here are the meanings of these codes. 

Rim Width 

The number 7 as the first number in the code indicates the width of the rim in inches. If the number is higher, then the width is also larger. Typically, rim widths commonly found range from 5 to 9.5 inches. However, there are some car rims that are wider depending on the type. 

Flange Distance

After the number 7, there is the letter 'J'. Usually, the letter J code is used for rims with a diameter of 15 inches. Meanwhile, for larger rim diameters, two capital letters are used, for example, 'JJ'. 

The difference between the two is not just about diameter, but also about the flange distance from the mounting point. The height of the flange distance for J rims is 17.5 mm while JJ is 18 mm. The correct calculation of flange distance aims to prevent the car tire from easily detaching. 

Rim Diameter 

The next number, as in the example, is 16. This number is known to indicate the size of the car rim diameter based on inches. The number can vary from 13 to 22 inches depending on the brand and type of car. 

Rim Hump 

The code H2 after the number 16 indicates the hump model or the contour model of the rim. This contour serves to prevent the tire from shifting while driving. 

The hump is used as the bead seat of the tire. In addition to H2, some types of rim humps include H, FH (Flat Hump), FH2 (Double Flat Hump), CH (Combination Hump), EH2 (Extended Hump), and EH2+ (Extended Hump +). 

Rim Offset 

The last code on the car rim is ET 45, which represents the offset or the magnitude of the cross-section surface or the surface in the middle of the rim. ET itself is derived from the German term Einpress Tieffe. 

This offset is also depicted with positive and negative numbers. If it says ET45, it means the rim offset shifts outward by 45 mm from the centerline of the rim. This means that the larger the rim offset or positive number, the more the bolt hole cross-section will protrude outward or approach the rim lip. 

PCD 

PCD (Pitch Circle Diameter) is the number of bolt holes on the rim measured based on the diameter formed by the number of those bolt holes. This code is usually placed separately and can be seen on other parts of the rim. 

The PCD code consists of numbers, for example, 4x114.3 or 5x114.5 and so on. The first number indicates the number of bolts and the subsequent number indicates the PCD size of 114.3 inches. 

When replacing car rims, it is important to pay attention to the rim size. Because if done carelessly, the result can make the car's appearance look odd and can even be dangerous. 

Choosing a car rim size that does not match the recommendations can make its appearance unproportional, tires often burst due to incorrect sizing, and car handling becomes more difficult. Therefore, try to choose car rims that are the same size as the old ones, or the size can go up or down slightly but still within reasonable limits. 

Author: Dinno Baskoro