How to measure Hubs, Rims and Tyres

Caravans and Trailers may have any sort of car rim so it is important to identify it correctly if you are getting spare parts.

Matching RIMS to HUBS

Hubs can be braked or non-braked and they attach your rim to the axle. The number of studs and the stud pattern is the first thing to define. If the stud size varies from our list it indicates a special RIM that we do not sell. eg. Valiant

Above: The PCD stands for Pitch Circle Diameter and goes through the centre of the studs. All our 6 stud wheels have a PCD of 139.70mm (5 1/2").

Above: For 5 studs we recommend the Adjacent Stud measurement. This is measured from the centres of the studs.

Table above: Shows measurements to define the Rim, you only need match either the PCD or the Adjacent dimension, whichever is easier to measure. The common hubs and rims are shown in the table with the FORD highlighted. Some measurements are shown as imperial as they are exact, I've included the metric sizes for what you need to measure.

The RIM size is also needed to match the TYRE size.

Above: The cutaway rim shows where the size is always measured in inches and it is measured where the rubber on the tyre fits on the shoulder of the rim. The width is measured between the shoulders as shown in the diagram.

---

Tyre specifications

What do all those numbers mean?

Tyres are best purchased from a local tyre dealer, but the above diagram explains what the markings on tyres mean.

Above: The load index is shown on the tyre, so you will need to use the table to see the load in Kgs that each tyre can hold. A dual axel trailer/caravan with a load index of 87 can support a total of 4 x 545 or 2,180kg**.

**If the axles or springs have a higher rating, the load will be limited by the tyres.