While buying a vehicle, it comes with perfectly fit wheels to connect with the suspension and gearing for a smooth ride and better vehicle performance. But that doesn’t mean you cannot change the wheels to suit the trending styles and upgrade it with a better model.
Also, there are circumstances when you accidentally hit a pothole, and you need a quick replacement. Without knowing the size of the wheel, you cannot be sure if it is the right choice for your vehicle. A good wheel makes all the difference and is vital to quality vehicle handling.
So, what comprises a wheel size? There are three parameters to it – diameter, width, and offset. Of these three, knowing the width is crucial when planning on changing the wheels. The wheel width may not be the first thing you check when purchasing a vehicle, but remember that measuring the correct width will ensure your tire appropriately fits on the rim.
This article will elaborate on the basics of wheel width, the right way to measure it, and the importance of knowing the wheel width for your unhindered vehicle ride.
Recommended Read: How to Measure Wheelbase?
What is wheel width?
There is a common misconception about the definition of wheel width. One might look at the wheel and say that the distance from the farthest back point to the front of the wheel is the wheel width.
It is wrong.
The wheel width or rim width is the distance from one bead seat to another. It is the point of contact between the tire and the wheel. It is expressed in millimeters or inches. Usually, the wheel width ranges between 6 inches to 14 inches.
For instance, if you check the back of the wheel, you will find a series of numbers denoting the size of the wheel. The first set of numbers after an alphabet is a wheel width.
But what if the numbers are missing or rubbed off? It can mislead you into buying the wrong sized wheels that can be costly and sometimes dangerous. It is why you should know how to measure the wheel width. The section below covers this in detail.
Materials used to measure the wheel width
Measuring the wheel width is simple. Indeed, you require only two tools –
Metallic tape measure – Measuring tapes are flexible rulers with markings to measure the distance or size. One side of the tape has the markings in metric units or imperial units. While measuring the wheel width, you can use metallic tape since it is durable, compact, and easier to calculate shorter measurements, unlike fabric tapes that stretch slightly and give incorrect readings.
Ruler – If you do not have metallic tape, you can use a straight edge ruler to measure the distance. You can place the ruler straight and use the measuring tape to find the length.
Alternatively, you can use a wire or a cable for markup.
How to Measure Wheel Width
It is better to dismount the wheel from the vehicle to get exact measurements. Although you can measure while the wheel is still mounted, it is easy to measure by dismantling it. A pro tip for you is to ignore the rim’s lips or outer part while measuring the wheel width.
Step 1: Place the wheel on the resting position
You must place the wheel on the table to see that it does not roll away. Since the wheel width determines the tire width, place the wheel on the table as it fits in the vehicle.
Step 2: Keep the hook of the tape in the inner side of the wheel and stretch
It is worth reiterating that the wheel width is measured from the bead seat where the tire rests perfectly on the wheel. Now, stretch the tape from one end of the bead seat to the other side. While doing this, ensure that you hold the tape straight, and it becomes taut like a rope.
Step 3: Stretch the tape to the other side and note the measurement.
The last step is to pull the tape to the other side of the wheel perpendicular to the center of the wheel. The value you observe from stretching from one bead to another gives the wheel width. The number must end in 0 or 0.5. If not, check for your measurement again.
How do different wheel widths affect the overall performance?
Now it comes to the most obvious question. Does the wheel width really matter? The answer is yes. It can increase or decrease the handling and stability of the vehicle, and in turn, affect the vehicle performance such as suspension, brake, acceleration, to name a few.
It affects the tire width
Wheel width is directly related to the tire width. If you mount a tire on a narrow wheel, the tire becomes narrow. However, every tire has a minimum and maximum wheel width, and if the tire is too wide than the wheel, it can fall off the rim.
If the wheel width is too narrow compared to the tire width, it will distort the tire sideways when taking a fast turn. If the wheel width is too wide than the tire width, it will give a harsh ride as there is not enough room in the sidewalls to furnish a smooth ride when fending off potholes or bumps.
Hence a sports car will have a wider wheel width because it gives better tire-road contact and becomes useful for off-roading. Winter tires are narrower and have narrow wheel widths to slice off easily on the snow.
Wider wheel width covers a better surface area
Larger wheels mean better grip. Yes, if the wheel width is more, it increases friction, and thus the tire holds on to the ground due to the larger surface area. Simply put, it gives the vehicle the right balance, the ability to maneuver, and improves stability.
Wheel offset and backspace: An overview
A good vehicle is characterized by many factors, in which selecting a proper wheel to fit the tire becomes predominant. After understanding A-Z about the wheel width, you have to be familiar with two other terms affecting the wheel size – offset and backspace. Both are necessary to determine how the wheel fits inside the frame.
At one glance, both terms appear the same, but they have a subtle difference. Let’s see each one in detail.
What is offset?
Your racer friend will tell you that varying the offset affects the vehicle maneuver. When you change the offset value, it changes the weight your tire puts on the ground.
Offset is the distance from the center line to the mounting surface wherein the wheels sit onto the vehicle. Offset is measured in millimeters, and it can take three values – positive, negative, and zero.
- Positive offset: The wheel will have a positive offset if the mounting surface is towards the face of the wheel.
- Negative offset: The wheel will have a negative offset if the mounting surface is towards the backside of the wheel.
- Zero offset: The wheel will have a zero offset if the mounting surface aligns with the center line.
To measure the offset, firstly, you need to find out the center line. How to do that? It’s simple. The center line is half the distance between the two bead points. So, mark the center line using a marker and measure the distance from this point to the mounting surface. It gives you the value of the offset.
Similarly, there are online offset calculators that you can use to determine the positioning of your new tire and wheel set up.
What is backspace?
Backspace is the distance from the mounting surface to the back edge of the wheel. The word “back” denotes the break side of the wheel. Increasing the backspace puts the tire closer to the center of the vehicle.
Backspace is measured in inches and is directly related to the offset. By changing the backspace value, it will immediately change the offset value.
To find the backspace, measure the distance from the inside lip of the wheel to the hub mounting surface.
A positive offset means greater backspace. Subtract the center line from the backspace, and you will get the offset value in inches.
A positive offset is normally seen in new and front-wheel drive vehicles.
So, the next time you want to replace your wheels, keep an eye on the offset and backspace values to help you tune the vehicle framework to the road conditions.
Your dream vehicle is what you make of it. Whether the car weight or the engine specifications, everything has its significance in the overall performance. But you cannot overlook the importance of wheel size, especially the wheel width.
Larger wheel width denotes that the wheels are thicker. If you skim through the vehicle manual, you find the wheel width, but, in general, you must know how to measure it to verify whether there is a manufacturing defect or while replacing a tire.
Wheel width is always measured from one bead seat to another and not from the outer section of the wheel.
As a racing enthusiast, you might have an urge to replace the stock wheels with wider ones but keep in mind that increasing wheel width can also adversely affect the suspension and hence, result in low fuel economy.
Similar to the wheel width, offset and backspace also contribute to vehicle performance. Both are directly related to one another. An offset can be positive, negative, or zero but, a backspace can have only a positive value.
A combination of wheel width, offset, and backspace impacts stability, noise, and comfort, among other things. A considerable amount of research goes into making the right wheel size to fit your tire. So, the next time you encounter someone saying what is in a wheel, you know what to say!