Times are hard and haulage firms are feeling the pinch. If you have a big 2-axle lorry and you need to carry more than it’s allowed, why not make it an extra set of wheels out of MDF and paint them to match the other wheels. Then your lorry will look ‘legal’ again when it’s actually 30% overloaded. This would cost a matter of a few pounds, compared to a few thousand to have an real extra axle fitted.