The wheel rim 'offset' is the distance between the centre line of the rim and the faceplate that bolts onto the hub. It is important to know as different offsets will alter the distance between the inside edge of the rim and the side of the trailer or caravan. It could also increase the overall width of the axle and it may also alter the capacity of a suspension system.
Start by placing the rim on a level surface with the front of the mounting plate facing upwards, then measure the distance 'A' (in millimetres) from the mounting plate edge to the surface.
Turn the rim over and measure the distance 'B' again as above.
Take distance B from A and divide by 2, this will give you the offset. If the result is a minus number then you have a Negative Offset. Rims with a negative offset are not usually found on trailers and caravans.
Please note: that if the rim edge is not flat on the surface when measuring B (due to the bulge in the rim) then the distance between the surface and the rim edge needs to be deducted from B before making the calculation.
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