Incorrect tyre pressure is the most common cause of premature tyre wear. Over inflation can be just as detrimental as under inflation. All tyre manufacturers construct a tyre that when correctly inflated, gives the tyre its optimum footprint on the road surface. So how do we determine what tyre pressure should be?
We can use two methods.
No.1 Method:
Calculate the load that the tyre is required to carry and then refer to the Tyre and Rim Association Manual, which will give you the correct pressure for that particular tyre. For example, 295 80r 22.5 Steer Tyre. Maximum weights over Steer Axle = 6000 kg’s. For instance: 3000 kg’s per tyre. The pressure required is 750 KPA or 109 PSI.
No.2 Method:
Static Laden Radius. Each tyre manufacturer will specify this dimension. In relation to a steer tyre the manufacturer will specify, e.g.497mm.
The measurement is taken from the road surface to the centre of the Stub Axle when the tyre is inflated, to give us as per the example 497mm. We now have the correct pressure in the tyre.
