Wheels are a crucial trailer component that must be compatible with the rest of the trailer’s design. In this blog, we’ll discuss how to determine the appropriate wheel size and bolt pattern for your trailer, as well as some other important considerations to bear in mind.
The Standard Trailer Wheel Size
First, let’s talk about the standard trailer wheel size. The most common sizes for trailer wheels are 13″, 14″, 15″ and 16″ in diameter, but it is always best to check your trailer’s specifications to ensure you use the correct size. This information can usually be found in the owner’s manual or on the manufacturer’s website.
Measuring Trailer Wheel Diameter
To measure trailer wheels, you will need to use a tape measure or ruler. Measure the diameter of the wheel by placing the end of the tape measure or ruler at the outer edge of the wheel rim and extending it to the other side of the wheel rim. This measurement will be the diameter of the wheel. You will also see this represented by the code that is moulded into the rubber tyre. Normally it will have an R before the diameter, ie R14 is a tyre size that will fit a 14” wheel. Wheel measurements in Australia are generally measured in inches.
Understanding the Trailer Wheel Bolt Pattern: Are all 5 Hole Trailer Rims the Same?
Next, let’s talk about the bolt/stud pattern on trailer wheels. The bolt/stud pattern refers to the number of holes on the wheel and the distance between them. The most common bolt/stud pattern for trailer wheels is 5 holes, but not all 5-hole trailer rims are the same. To measure the bolt/stud pattern, you will need to use a bolt pattern gauge or a ruler. Place the gauge or ruler over the wheel and measure the distance between the centre of one hole to the centre of the hole directly across from it. This measurement will be the bolt pattern PCD (pitch circle diameter). The true measurement of PCD is normally in inches (to a decimal point), however many in the industry approximate this to a measurement in mm. The most common 5 stud patterns in order of commonality are Ford, HT, HQ, Commodore, and Land Cruiser 5 stud. When measuring a 5 stud pattern it is more difficult as there is no opposing stud to get an accurate measurement. There are a number of other stud patterns that you will also find on trailers, the 4 stud and 6 stud. On 15 inch and 16 inch wheels the 6 stud is very common. On smaller wheels 8 inch to 10” the 4 stud is very common.
Determining the Bolt Pattern
The first number in the bolt pattern is the number of bolt holes. The second number denotes the diameter, in inches, of the circle on which the bolt holes sit.
On wheels with an even number of bolt holes, measure from the center of one bolt hole to the center of the hole directly across from it. (Example: 8 on 6-1/2 means 8 bolt holes with 6-1/2″ from the center of one hole to the center of another on the opposite side.)
To determine the bolt-circle diameter on wheels with an odd number of bolt holes, measure from the center of any bolt hole to the point halfway between the two bolt holes directly across from the first. (Example: 5 on 4-1/2 means 5 bolt holes with 4-1/2″ measured to a point halfway between the opposite bolt holes.)
How to Identify PCD
 | You can measure from centre to centre or from outside edge to inside edge to get PCD. STUD NUMBERSTUD TO STUDPCDMINI471mm 4” (101.6mm)DATSUN480mm 4 ½” (114.30mm)HT565mm 4 ¼” (107.95mm)HQ571mm 4 ¾” (120.65mm)Comm570mm 120mmFord567mm 4 ½” (114.30mm)TL5588.5mm 150mmTL6669mm 5 ½” (139.70mm)F100584mm5 ½” (139.70mm) |
Measuring the distance (D) from the centre of one bolt hole on the wheel to the centre of a bolt hole right next to it can also help to determine the bolt pattern.
- If D = 2-5/8″, then the bolt pattern is 5 on 4-1/2″
- If D = 2-3/4″, then the bolt pattern is 5 on 4-3/4″
- If D = 3″, then the bolt pattern is 5 on 5″
- If D = 3-1/4″, then the bolt pattern is 5 on 5-1/2″
How to Identify Tyre Wall
Construction type
This tells you whether the tyre is a radial or bias-ply construction.
Vehicle rating
This tells you the type of vehicle the tyre is designed for, such as “ST” for special trailer.
Diameter
This tells you the size of the tyre in inches.
Speed rating
This tells you the maximum speed at which the tyre can be safely operated. It is a letter, such as “M” for a maximum speed of 81 mph.
The Importance of Weight Rating in Trailer Wheels
Finally, it’s important to note that not all wheels are created equal, even if they have the same size and bolt pattern. Some wheels are designed specifically for trailers and have a higher weight rating to handle the added weight and stress of towing. It is always recommended to check the weight rating on the wheel before purchasing it.
Ensuring Safe and Compatible Trailer Wheels
In conclusion, when looking for new wheels for your trailer, it is essential to ensure the correct size, bolt pattern, and weight rating. Always check your trailer’s specifications, and measure the wheel diameter and bolt pattern to ensure compatibility. By taking these steps, you will know that your trailer is safe and ready to hit the road. If you’ve successfully determined the wheel size and bolt pattern for your trailer, visit Oz Hitch’s online shop for a wide selection of compatible trailer wheels. And if you still have questions or need assistance, don’t hesitate to contact our experienced staff for help with any of your trailer needs.
