What do J and ET mean in wheel data?
2 Answers
The width of the wheel is 7J or 8J. Here, the number represents the width of the wheel, while J represents the shape and height of the wheel flange. The ET value, also known as the ET offset, refers to the Off-set value, which is the deviation between the mounting surface of the wheel and the centerline of the rim, measured in millimeters. It can be positive, zero, or negative. Here is more related information: Considerations for J value during installation: Many car enthusiasts encounter various issues during wheel modification. For example, if the original wheel is 6JX15 inches and the original tire is 195/65/15, but you want to install a wheel with a width of 8JX17 inches, the standard tire should be 235/45/17. However, flatter tires are harder to find. During the modification process, based on the J value, you need to consider what you want to achieve when selecting the tire width. Choosing a point within the range affects both handling and ride comfort (comfort). A middle value balances both (but may slightly compromise both). Narrower tires affect handling, while wider tires affect comfort. Considerations for ET value during installation: Changing the wheel's Offset alters the wheel track, which is the distance between the centerlines of the tires. Simply increasing the wheel and tire size without changing the Off-set does not affect the wheel track. Impact of changing Off-set: Using a wheel with a smaller positive Off-set value widens the wheel track, reducing body roll during turns and improving cornering speed limits. However, it also increases the distance between the steering axis center and the tire center, making steering more difficult and increasing the load on the steering mechanism. This leads to greater deformation of the steering linkage, so Toe-in adjustments may be necessary to compensate.
Having played with cars for so many years, I'm extremely familiar with wheel specs like J and ET. J refers to the width of the wheel in inches—for example, 7J means 7 inches wide. It determines how wide a tire you can fit; too narrow and it's unstable, too wide and it might rub against the brakes or fenders. ET is the offset in millimeters, which affects the wheel's mounting position. A positive ET means the wheel sits more inward, while a negative ET makes it protrude outward. When modifying, a low ET might look cool with the wheels sticking out, but on rough roads, it can easily scrape the body. Once, I installed wheels with an ET20, and during high-speed turns, the tires hit the suspension, forcing me to redo the setup. I recommend sticking close to the factory specs and not just focusing on looks. Also, J and ET values are usually stamped on the inner side of the wheel or in the manual—measure to avoid mistakes. Safety and practicality come first; reckless modifications can lead to accidents and wasted money.
