... function, which enable trailer to brake always prior to tractor truck in order to ensure the brake safetyof train ... the truck.5.spare wheel carrier is installed on tractor trucks as standard item.Product DescriptionTractor truck model:ZZ4257N3241WDriving ... 12.00-20,12.00R20Fuel Tank( L) 350 HOWO 6X4 TRACTOR TRUCK :OTHERS MODEL:ZZ4257M3241W,ZZ4257M3241V, ZZ4257N3241W, ZZ3257N3241V, ZZ4257S3241W, ...