GTM is the maximum weight ( as set by the manufacturer ) the trailer may apply through the trailer ’ s tyres . In this specification , the trailer is fully loaded .
 AGGREGATE TRAILER MASS VSB 1 STATES :
 ATM is the total mass of the trailer when carrying the maximum load recommended by the manufacturer . ATM includes the mass imposed on the towing vehicle , when the combined tow vehicle and trailer are resting on a horizontal surface .
 Note : The maximum load the trailer can carry is the same when determining both GTM and ATM .
 ATM is the maximum weight acting downwards through both the trailer tyres and the trailer coupling the trailer is designed for . In this specification , the trailer is fully loaded .
 PAYLOAD CAPACITY
 When it comes to establishing a caravan ’ s payload , Revision 6 of VSB 1 offers the following :
 How does Tare Mass and Aggregate Trailer Mass ( ATM ) determine how heavy a load can be carried on trailer ?
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