How are towing weights calculated and how much is it safe to tow?

My understanding of towing capacity is that it is based on the kerbweight of the vehicle. Most manufacturers recommend 85% of gross kerbweight. So how come so many large 4x4s can tow way above that weight? I was thinking it was torque related but even automatic transmission models seem to have much larger than kerbweight capacities and they have no.where near the torque

Asked on 21 August 2019 by Jez

Answered by Dan Powell
You are correct about the 85% rule - the trailer/caravan is best being less than 85% of the weight of the towing vehicle for safe stability. You should also consider the noseweight (which is the weight the trailer/caravan puts on the towbar). The noseweight should be between 5-7% of the weight of the trailer/caravan.

You should never tow anything without knowing the individual and combined weights of your car (and the trailer or caravan). The Gross Vehicle Weight (GVW) or Maximum Authorised Mass (MAM) tells you how much a vehicle or a trailer can legally weigh in order to be used on the road, while the Gross Train Weight (GTW) or Gross Combination Weight (GCW), is the total, permitted weight of the vehicle, the trailer and everything it’s carrying.

You can find these figures on the van or trailer’s chassis plate, in the handbook and sometimes on the V5C registration certificate.
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