Wheel width and tire matching

As we all know, wheel hubs come in a variety of diameters, ranging from as small as 14 inches to as large as 24 inches and above. However, wheel hubs also have different widths. The width of a wheel hub not only affects its installation on a vehicle but also the installation of the tire on the hub. Below is a detailed explanation.

Wheel Hub Size

The size of a wheel hub is defined as "diameter x width"; therefore, a 17-inch wheel hub could be 17x7.0, 17x7.5, or 17x8.0.

The width of a wheel hub usually increases proportionally with its diameter; therefore, you will rarely see 17x5.0 or 17x10 hubs. Standard sizes are 14x5.0 and 19x10.

The diameter of a wheel hub is easy to determine; it is usually the third number in the tire size. For example, 235/45/17 means that this tire is suitable for a 17-inch wheel hub. However, the width of the wheel hub is not so easy to determine. Because the width value of most wheel hubs is engraved on the back of the spokes, the wheel hub must be removed to read it. If the value is not engraved on the back, it needs to be measured in practice using a tape measure from the inner side of each wheel flange where the tire contacts the hub; do not measure the outer edge of the hub.

Front and Rear Matching

Many high-end rear-wheel-drive vehicles, especially BMWs and Mercedes-Benzs, have wider rear wheels than front wheels. This type of wheel hub is called "front and rear matching." The rear wheels and tires of the "front and rear matching" configuration are wider, providing a larger contact area, which is a good thing, but there are also some details to note. First, "front and rear matching" means that the front and rear wheels cannot be interchanged because while the front wheels can be fitted to the rear, the rear wheels cannot be fitted to the front and will cause friction between the tires and the body.

In addition, the tire sizes of the front and rear wheels are different, which means that care must be taken when purchasing and installing tires to ensure that the tire size is correct and accurately installed on the matching hub.

Tire Matching

Like wheel hubs, tires also come in a variety of widths. The determined tire width is determined in accordance with the corresponding wheel hub width, meaning that the tire has sufficient width to fit the hub. However, in practice, there are often cases of narrow tires being installed on wider hubs. That is, for a tire that is originally not wide enough, the tire sidewall is stretched to make it fit, so the tire sidewall, which should be perpendicular to the tire tread, is tilted. This problem is easy to identify and is extremely bad because only when the tire sidewall is perpendicular to the tread can it effectively bear weight and protect the hub in a collision.

Worse yet, many people, especially teenagers, see this useless and dangerous condition as a trend, as if the stretched appearance of the tire can somehow mask the fact that the tire sidewall is tilted at a 45-degree angle to the hub.

I encounter this situation at least once a month:

“Do you know your tires aren't wide enough?”

“It's a ‘stretched’ look.”

“Yes, it is this ‘stretched’ look that is ruining your tires and making your hubs look ugly.”

You can show off your personality on your car, but unless it's for rocking, don't install narrow tires on wide hubs. Responsible tire installers will have a book listing the specified tire widths for certain wheel widths and will never install tires that are not wide enough for the car owner.