Max tow weights

[WAK]

Hi, thanks to all who replied to my question about aerodynamics, however, heres another 1 that puzzles me,

i have noticed that with some car manufacturers they quote a Max tow weight higher than the kerbweight, some quote Max tow weight lower, i was of the understanding that you tried to stick to 85% of the cars kerbweight, so whats all this about with the Max tow figures.

Thanks Wak.

 

[Charles_5040035]

Hi Wak,

Firstly the 85% is an advisory limit to ensure a significant safety margin between the kerb weight of the towing vehicle and the maximum permitted loaded weight of the trailer. A more experienced driver may exceed this advisory limit but obviously the safety margin is reduced and the likelyhood of the "tail wagging the dog" is greater.

However, the maximum towing weight is the maximum that the vehicle capable of restarting up a 1:12 slope and is set by the vehicle manufacturer. It is not related to the kerbweight of the vehicle but rather its power and must never be taken as an indication of a safe match. The maximum towing weight must never be exceeded, as if you do, it will invalidate any warranty on you towing vehicle and more importantly your insurance!!!

I hope that this is useful

Regards

Charles

 

[ProfJohnL]

Hello Wak, All cars sold in the UK are required to state a maximum permitted tow load. This is not a simple fixed proporton of the kerbweight of the tow vehicle, but is derived from a number of tests that measure the vehicles ability to cope with an additional towed mass, such as hill starts and engine cooling amongst others. It is quite possible for some cars to produce results that allow maximum permitted towed loads that exceed the cars kerbweight, and some that are significantly less than the kerbweight. Some are even less than the often quoted guide figre of 85%. to remain road legal you must not exceed this figure or any other limiting values defined by the manufacturer (axle and tow hitch etc) You must always check you vehicles specifications. It is always sensible to have a car that is heavier than its trailer, but the most important factor is good driving makeing allowance for the extra weight of a trailer and its effect on the tow vehicle.

 

[Lutz]

I can only confirm what John L and Charles have written, although there are more factors that determine the car manufacturer's quoted towload limit: brake and clutch performance, in the case of automatic transmissions gearbox cooling as well as the engine cooling and last but not least, the vehicle underbody structure. Some manufacturers even specify different max towloads for caravans than for very low sided trailers. The 85% advisory only applies to caravans.

 

[itsmeonpcv]

I can only confirm what John L and Charles have written, although there are more factors that determine the car manufacturer's quoted towload limit: brake and clutch performance, in the case of automatic transmissions gearbox cooling as well as the engine cooling and last but not least, the vehicle underbody structure. Some manufacturers even specify different max towloads for caravans than for very low sided trailers. The 85% advisory only applies to caravans.

So if the max tow weight is less than the kerbweight then go by the max tow weight. Or do we ignore the max tow weight and apply 85% of the kerbweight.

I thought I had this sorted out with my RAV4 (5dr) max tow weight 1500kg onto an Avondale Mendip??????