When selecting a tire and wheel combination for your ATV/UTV, it is important to understand how manufactures and retailers identify different tire and wheel sizes.
For example, when you search through the many different wheel sizes available for any given ATV/UTV, it is common to find numbers such as: 12x7, 4/110, 4+3. We will explain how these numbers work using the illustration above.
The numbers "12x7" indicate the height and width of the wheel measuring from the beads where the tire sits on the rim: 12 inches tall by 7 inches wide (see illustration above).
The numbers "4/110" refer to the bolt pattern and bolt pattern distance between holes. In this example, the "4" is the number of bolt holes, and the "110" is the distance between two opposite holes in millimeters.
The "4+3" is the wheel offset measurement. This means that the mounting hub is offset 4" from the back of the wheel (vehicle side), and 3" from the front of the wheel (street side). This shows where the mounting hub is located in relation to the center of the wheel. If the measurement said "3.5+3.5", the mounting hub would be centered, and would have a "0" offset.
Measuring Offset distance
Using the "4+3" approach is a popular method to measure the offset on wheels. Using a straight edge, you can measure from the back of the wheel down to the mounting hub (see illustration below) to get "4", also known as your backspacing measurement. Since the wheel is 7" wide, your front offset will be the remaining "3".
Positive and Negative Offset
It is not uncommon to see an offset value for a wheel referenced off the centerline of the wheel. Many sizing charts, especially in street applications, express the offset distance in millimeters from the center of the wheel (see diagram below). If the mounting hub is closer to the outside (street), then it has a positive offset. If the hub is closer to the inside of the wheel (vehicle side), then it has a negative offset. While using a large negative offset can help accommodate larger tires and wheels, improve stability, and look cool, the wider stance can also cause steering geometry issues like bump-steer, and fatigue wheel bearings.
The first two measurements on a tire refer to the height and width. The tire in the illustration below is 28 inches tall, 10 inches wide, and fits a 12 inch wheel.