Choosing the right trailer wheel is not as straightforward as it might seem. Get the size wrong and the wheel will not fit, or worse, it will fit but not safely. This guide covers everything you need to know: wheel diameter, PCD, stud pattern and tyre size, so you can order with confidence. Browse our full range of trailer wheels and tyres to find the right option for your trailer.
Start with the wheel diameter
Trailer wheels are sized by the diameter of the rim, measured in inches across the inside of the wheel where the tyre sits. The most common sizes used on UK trailers are 8", 10", 12", 13", 14" and 16".
As a general rule, smaller and lighter trailers use smaller diameter wheels, while larger commercial or plant trailers use 14" or 16" wheels. If you are replacing a wheel like for like, the diameter will be marked on the sidewall of your existing tyre.
Understanding PCD (Pitch Circle Diameter)
PCD refers to the diameter of the circle on which your wheel's stud holes sit. It is one of the most important measurements to get right. A wheel with the wrong PCD will not bolt onto your hub correctly.
PCD is expressed as the number of studs followed by the circle diameter, for example 4/100 (four studs on a 100mm circle) or 5/112. Common trailer PCDs in the UK include:
• 4/100mm
• 4/140mm (4 x 5.5")
• 5/165mm (5 x 6.5")
To measure your PCD, measure between the centre points of two studs directly opposite each other on a four-stud hub. If you are not sure, call our team on 01962 774 988 and we can help you identify it.
Check the stud count and size
As well as PCD, you need to match the number of studs and the stud diameter. UK trailers typically use four or five-stud configurations. The stud size is usually M12 or M14 for metric hubs, or 1/2" for imperial hubs.
If you are replacing a wheel on an Ifor Williams trailer, most models use a 4/114.3 (4 x 4.5") PCD with M12 studs. Always check the hub specification before ordering.
Reading the tyre size
The tyre size is marked on the sidewall of your existing tyre. It is displayed as a sequence of numbers, for example 195/55 R10. Here is what each part means:
• 195 is the tyre width in millimetres
• 55 is the aspect ratio (the height of the sidewall as a percentage of the width)
• R indicates radial construction
• 10 is the wheel diameter in inches
If your tyre is showing signs of wear or cracking, it is worth checking your trailer bearings at the same time. It is also advisable to replace both tyres together, even if only one is visibly damaged.
Complete wheel assemblies vs rims and tyres separately
If you want a straightforward replacement, a complete wheel assembly (rim and tyre already fitted together) is the easiest option. TrailerTek stocks complete assemblies across all common sizes, ready to bolt straight on.
If you are building a trailer from scratch or need a specific tyre specification, you can also buy rims and tyres separately and have them assembled to order.
Not sure? We can help
If you have checked your existing wheel and are still unsure which replacement to order, call our team on 01962 774 988. We stock trailer wheels across all common sizes and PCDs and can help you identify the right fit before you order.
Browse the full range of trailer wheels and tyres at TrailerTek.
