Driving and operating 153Driving characteristics andtowing tipsBefore attaching a trailer, lubricatethe coupling ball. However, do not doso if a stabiliser, which acts on thecoupling ball, is being used to reducesnaking movements.For trailers with low driving stabilityand trailers with a permitted grossvehicle weight of more than 1400 kgthe use of a stabiliser is stronglyrecommended when driving above50 mph (80 km/h).If the trailer starts snaking, drive moreslowly, do not attempt to correct thesteering and brake sharply ifnecessary.When driving downhill, drive in thesame gear as if driving uphill anddrive at a similar speed.Adjust tyre pressure to the valuespecified for full load 3 215.Trailer towingTrailer loadsThe permissible trailer loads arevehicle-dependent and engine-dependent maximum values whichmust not be exceeded. The actualtrailer load is the difference betweenthe actual gross weight of the trailerand the actual coupling socket loadwith the trailer coupled.The permissible trailer loads arespecified in the vehicle documents. Ingeneral, they are valid for gradientsup to max. 12 %.The permitted trailer load applies upto the specified incline and up to analtitude of 3300 ft (1000 metres)above sea level. Since engine powerdecreases as altitude increases dueto the air becoming thinner, thereforereducing climbing ability, thepermissible gross train weight alsodecreases by 10 % for every 3300 ft(1000 metres) of additional altitude.The gross train weight does not haveto be reduced when driving on roadswith slight inclines (less than 8 %, e.g.motorways).The permissible gross train weightmust not be exceeded. This weight isspecified on the identification plate3 199.Vertical coupling loadThe vertical coupling load is the loadexerted by the trailer on the couplingball. It can be varied by changing theweight distribution when loading thetrailer.The maximum permissible verticalcoupling load (85 kg) is specified onthe towing equipment identificationplate and in the vehicle documents.Always aim for the maximum load,especially in the case of heavytrailers. The vertical coupling loadshould never fall below 25 kg.
