We tow a 23D with a 2007 Mercedes ML320 CDI diesel. We found that at 35 mph on a 6% downgrade, the engine would control the speed without brake usage. The scales reported we were around 11,250 pounds loaded for camping.
The message is slow down on descents to conserve the brakes and a sudden emergency situation is handled much easier.
WBCCI Life Member 5123, AIR 70341, 4CU, WD9EMC
TV - 2012 Dodge 2500 4x4 Cummins HO, automatic, Centramatics, Kelderman level ride airbag suspension, bed shell
2014 31' Classic model 30 twin beds, 50 amp service, 900 watt solar system, Centramatics, Dill TPMS, disc brakes, 16" tires & wheels