الهيئة السعودية للمواصفات و المقاييس و الجودة  
Saudi Standards, Metrology and Quality Org(SASO)  
 
 
 
DRAFT: FINAL  
 
 
SASO /FDS /  31259:  2018  
 
 
 
TRAILER - GENERAL REQUIREMENTS  
 
 
 
 
 
 
ICS: 43.040  
 
THIS DOCUMENT IS A DRAFT SAUDI REGULATION CIRCULATED FOR 
COMMENT. IT IS, THEREFORE SUBJECT TO CHANGE AND MAY NOT BE 
REFERRED TO AS A SAUDI REGULATION UNTIL APPROVED BY THE 
BOARD OF DIRECTORS.  
 
 
   
   
 
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 SASO STANDAR D  SASO 31259 :0000  
1. SCOPE AND FIELD OF APPLICATION  
                       
1.1 This standard is concerned with general  requirements  for trailers and semi -trailers 
ensuring high levels of safety, Environmental protection, energy efficiency  and antitheft 
performance  for detailed  requirements refer to  SAUDI STANDARDS  METROLOGY 
QUALITY  ORGANIZATION (SASO ) Technical  Regulations  on the subject concerne d.  
1.2 SASO  techn ical regulation related to  vehicles will be  formulated based on  UNITED 
NATIONS ECONOMIC COMMISSION FOR EUROPE UN/ECE  regulation  in the case of  
vehicles manufactured  in compliance with  FEDERAL MOTOR VEHICLE SAFETY 
STANDARDS FMVSS regulations,  will be accepted as an alternative .     
1.3 The provisions of this standard apply to all trailers and semi -trailers industry designed for road 
circulation .  
This standard does not cover the armed services trailers .  1.4                      
2.  COMPLEMENTARY REFERENCES   
2.1 The following codes, standards and regulations are used as reference documents in the 
compilation of this standard.  
 
STANDARD TITLE  STANDARD  
Motor Vehicles - General Requirements  SASO GSO 42 2.1.1  
Uniform provisions concerning the approval of vehicles with 
regard to the installation of lighting and light -signaling devices  SASO GSO ECE 48 2.1.2 
Uniform provisions concerning the approval of tires with regard to 
rolling sound emissions and/or to adhesion on wet surfaces and/or to 
rolling resistance  SASO GSO ECE 117 2.1.3 
Road vehicles -- Installation of lighting and light signaling  
devices for motor vehicles and their trailers SASO ISO 303 2.1.4 
Road vehicles -- 50 semi -trailer fifth wheel coupling pin -- Basic and 
mounting/interchangeability dimensions SASO ISO 337 2.1.5 
Motor Vehicles Conformity Certificates SASO 400 2.1.6 
Motor Vehicles – Dimensions and Weights  SASO 469 2.1.7 
Road Vehicles - Retro -Reflective Number Plates and Its Methods of 
Test SASO 572 2.1.8 
Road vehicles -- Dimensions of motor vehicles and towed vehicles -- 
Terms and definitions SASO ISO 612 2.1.9 
Motor Vehicle - Conformity Certificates for Vehicle Manufactured in 
Multi -Stages  SASO 703 2.1.10 
Road Vehicles - Types — Terms and Definitions  SASO 1071 2.1.11 
Road vehicles -- Coupling balls for caravans and light trailers  --  
Dimensions SASO ISO 1103 2.1.12   
   
 
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 SASO STANDAR D  SASO 31259 :0000  
Multi -Purpose Vehicles, Trucks, Buses and Trailers Tires Part 1: 
Nomenclature, Designation, Marking, Dimensions, Load Capacities 
and Inflation Pressures SASO 1134 
 2.1.13 
Multi -Purpose Vehicles, Trucks, Buses and Trailers Tires  
- PART 2: Methods of Test SASO 1135 2.1.14 
Multi -Purpose Vehicles, T rucks, Buses and Trailers Tires  
Part 3: General Requirements SASO 1136 2.1.15 
Road vehicles -- Connectors for the electrical connection of towing and 
towed vehicles -- 7-pole connector type 24 N (normal) for vehicles 
with 24 V nominal supply voltage SASO ISO 1185  2.1.16 
Retreaded pneumatic tires for trucks and their trailers SASO 1275 2.1.17 
Transportation of Dangerous Substances by Road - Part 1: General 
Safety Requirements SASO 1285 2.1.18 
Transportation of Dangerous Substances by Road 
- Part 2: Transportation of Radioactive Materials  SASO 1286 2.1.19 
Transportation of Dangerous Substances by Road 
- Part 3: Transportation of Petroleum Liquid SASO 1287 2.1.20 
Transportation of Dangerous Substances by Road  -  
Part 4: Transportation of Explosive Materials  SASO 1288 2.1.21 
Road vehicles -- Connectors for the electrical connection of towing and 
towed vehicles -- 7-pole connector type 12 N (normal) for vehicles 
with 12 V nominal supply voltage SASO -ISO-1724  2.1.22 
Road vehicles -- Mechanical coupling between tractors and semitrailers  
-- Part 1: Interchangeability between tractors and semi -trailers for 
general cargo SASO ISO 1726 -1  2.1.23 
Road vehicles -- Mechanical couplings between tractors and 
semitrailers -- Part 2: Interchangeability betw een low -coupling tractors 
and high -volume semi -trailers  SASO ISO 1726 -2  2.1.24 
Road vehicles -- Mechanical couplings between tractors and 
semitrailers -- Part 3: Requirements for semi -trailer contact area to fifth 
wheel SASO ISO 1726 -3  2.1.25 
Motor Vehicles Tires -- Temporary Use Spare Wheels/Tires and Their 
Methods of Test SASO 1771 2.1.26 
Motor vehicles -lateral protection of truck and trailer and its methods of 
test SASO GSO 2113 2.1.2 7  
Motor vehicles -rear under run protective devices for truck a nd trailer 
and its methods of test SASO GSO 2114 2.1.2 8  
Motor Vehicle - Vehicle Identification Number (VIN)  
Requirements SASO 2249 2.1.29  
Motor vehicles - world manufacturer identifier code  SASO 2250 2.1.3 0  
Motor vehicle - VIN-location and attachment  SASO 2251 2.1.3 1  
Road Vehicles - Bottom Loading Tank Truck  & trailer  SASO  2288  2.1.32 
Road vehicles -- Safety glazing materials -- Vocabulary  SASO ISO 3536 2.1.33 
Road vehicles -- Drawbar couplings -- Interchangeability  SASO ISO 3584 2.1.3 4  
Road vehicles -- Connectors for the electrical connection of towing and 
towed vehicles -- 7-pole connector type 24 S (supplementary) for 
vehicles with 24 V nominal supply voltage SASO ISO 3731 2.1.3 5  
Road vehicles -- Types -- Terms and definitions  SASO ISO 3833  2.1.3 6  
Road vehicles -- Fifth wheels -- Interchangeability  SASO ISO 3842 2.1.3 7  
Road vehicles: Wheels/rims for commercial vehicles - Test methods  SASO GSO ISO 
3894 2.1.3 8  
Road vehicles -- 90 semi -trailer fifth wheel kingpin -- 
Interchangeability  SASO ISO 4086 2.1.3 9    
   
 
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 SASO STANDAR D  SASO 31259 :0000  
Road vehicles -- Connectors for the electrical connection of towing and 
towed vehicles -- Definitions, tests and requirements  SASO ISO 4091 2.1.40  
Commercial vehicles -- Wheel -hub attachment dimensions  SASO ISO 4107 2.1.41  
Road vehicles -- Connectors for the electrical connection of towing and 
towed vehicles -- Part 1: Connectors for braking systems and running 
gear of vehicles with 24 V nominal supply voltage SASO ISO 7638 -1  2.1.4 2  
Road vehicles -- Connectors for the electrical  connection of towing and 
towed vehicles -- Part 2: Connectors for braking systems and running 
gear of vehicles with 12 V nominal supply voltage SASO ISO 7638 -2  2.1.4 3  
Road vehicles -- Fifth wheel kingpins -- Strength test  SASO -ISO-8716  2.1.4 4  
Road vehicles -- Vehicle dynamics and road -holding ability  --  
Vocabulary SASO ISO 8855 2.1.4 5  
Road vehicles -- Determination of center of gravity  SASO ISO 10392 2.1.4 6  
Road vehicles -- Connectors for the electrical connection of  
towing and towed vehicles -- 13-pole connectors for vehicles  
with 12 V nominal supply voltage SASO ISO 11446 2.1.4 7  
Road vehicles -- Connectors for the electrical connection of towing and 
towed vehicles -- 15-pole connector for vehicles with 24 V nominal 
supply voltage SASO -ISO-12098  2.1.4 8  
Road vehicles — LED lamp characteristics for bulb compatible failure 
detection — Part 1: LED lamps used as direction indicators  SASO GSO ISO 
13207 -1  2.1.4 9  
Road vehicles -- Tests for rigid plastic safety glazing materials  SASO ISO 15082  2.1.50  
Road vehicles -- Degrees of protection (IP code) -- Protection of  
electrical equipment against foreign objects, water and access SASO ISO 20653 2.1.51  
Road vehicles — Drawbar couplings, drawbar eyes, fifth wheel 
kingpins, hook couplings and toroidal eyes — Wear limits for in -use 
mechanical couplings SASO GSO ISO/TS 
20825 2.1.52  
 
3.  DEFINITIONS 
For the purposes of this regulation the following def initions shall apply in addition to the 
definitions set out in list of standards paragraph  (2).  
3.1 Automotive Trailers (O Category) :  
A non-self-propelled  vehicle having at least two wheels which on account of its design  and 
technical features is used to transport goods and is intended to be towed by a motor vehicle; 
semi -trailer is included in this category .  
:1 Category O 3.1.1 
Trailers with a maximum mass not exceeding 0 .75 tons.  
:2 Category O 23.1. 
Trailers with a maximum mass exceeding 0.75  tons but not exceeding 3. 5 tons.  
:3 Category O 33.1. 
Trailers with a maximum mass exceeding 3. 5 tons but not exceeding 10  tons.    
   
 
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 SASO STANDAR D  SASO 31259 :0000  
:4 Category O 43.1. 
Trailers with a maximum mass exceeding 10  tons.  
3.2   Tractor :  
 A truck (provided with fifth wheel) designed primarily for drawing a semitrailer and not so 
constructed as to carry a load other than a part of the weight of the semitrailer .     
3.3 Truck :  
 A motor vehicle intended  for carrying goods,  or towing a trailer .  
3.4 Vehicle :  
 Any motor vehicle or its trailer .  
3.5 Semi -trailer :  
A trailer, wh ich is intended to be connected to a motor vehicle and which is so co nstructed 
that a portion of it is superimposed on and apart of whose weight is borne by the  haulage 
tractor .  
3.6 Drawbar trailer :  
A towed vehicle with at least two axles, of which at least one is a steered axle, and :   
  — Equipped with a towing d evice which can move vertically  (in relation to the trailer) ,  
  — Which  transmits no significant static vertical load to the towing  2 vehicle (less than 100       
daN).   
When a semi -trailer is coupled to a dolly axle it is considered to be a drawbar trailer .  
3.7 Maximum (gross) vehicles weight (GVW) :  
 Weight of the vehicle loaded with the maximum load specified by the manufacturer .  
3.8 Maximum (gross) axle weight (GAW) :  
 The maximum load carrying  capacity, specified by the manufacturer, of a single axle 
measured at the tyre -ground interfaces.  
3.9 Overhang :  
The horizontal distance (a bus, truck, trailer or semi -trailer) between the centers  of the rear 
most axle and the rear most  part of the body, or between the center of the front most axle and 
the front most part of the body .  
3.10 Drawbar :  
Strut  or column like device temporarily attached  between the rear of a towing vehicle and the 
front of the vehicle  being towed. Its purpose is to maintain the interval or distance  between 
the two.  
   
   
 
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 SASO STANDAR D  SASO 31259 :0000  
3.11 Fifth  Wheel Coupling:  
A device used to connect a tractor to a semi -trailer and to permit articulation between the 
units. It is  generally composed of a lower half, mounted on the tractor , consisting  of a 
trunnion, plate and latching mechanism, for  connection with a king pin mount ed on the semi -
trailer.  
3.12 King pin:  
The trailer part of the mechanical coupling of a  transport trailer normally attached to fifth 
wheel of the tractor.  
3.13 Group of axles:  
Axles  being part of a bogie. A two axle  group is called a tandem and a t ri-axle group a tri -axle 
bogie. By convention, a solo axle is considered as a group of one axle.  
3.14 Axle end :  
Group of tyres on one of the axle ends bearing half the  load lying on the axle end .  
3.15 Air suspension :  
A suspension system on which at least 75%  of the spring effe ct is caused by the air spring .  
3.16 Spray -suppression system : 
A system intended to reduce the pulverization of water thrown upwards by the tyres of a 
vehicle in motion. The spray -suppression system is variously made up of a mudguard, rain 
flaps and valances equipped with a spray -suppression device.  
3.17 Vehicle identification number VIN:  
Structured combination of characters assigned to a vehicle by the manufacturer for 
identification purposes . 
3.18 World manufacturer identifier WMI : 
First section of the vehicle identification number, which designates  the manufacturer of the 
vehicle and is assigned to a vehicle manufacturer in order to allow identification of that 
manufacturer . 
  NOTE : When used in conjunction with the remaining sections of  the VIN, the WMI ensures  the           
uniqueness of the VIN for all  vehicles manufactured in the world for a period of 30 years.  
3.19 vehicle descriptor section VDS : 
Second section of the vehicle identification number, which  provides information describing 
the general attributes of the  vehicle . 
3.20 Vehicle indicator section VIS :   
   
 
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 SASO STANDAR D  SASO 31259 :0000  
Third and final section of the vehicle identification number, which  constitutes a combination 
of characters assigned by the manufacturer to distinguish one vehicle from another . 
3.21 Incomplete trailer :  
Any trailer which must undergo at least  one further stage of completion in order to meet the 
relevant  technical requirements of this Directive .  
3.22 Complete trailer :  
 Any trailer which need not be completed  in order to meet the relevant technical requirements 
of this  Directive .  
3.23 System :  
 An assembly of  devices combined to perform one  or more specific functions in a trailer and 
which is subject to the requirements of any of the regulatory acts .  
3.24 Separate  technical unit :  
 A device subject to the  requirements of a regulatory act and intended to be part of a  trailer , 
which may be typ e-approved separately, but only in relation  to one or more specified types of 
trailer where the regulatory act makes express provisions for so doing .  
3.25 Information document :  
The document set in the corresponding Annex to a separate directive,  or regulation that  
prescribes the information to be supplied by an  applicant, it being permissible to supply the 
information document in the form of an electronic file .  
3.26 Manufacturer :  
The person or body who is responsible to  the approval authority for all aspects of the type -
approval or  authorization  process and for ens uring conformity of production. It is not essential 
that the person or body be directly involved in all  stages of the construction of the vehicle, 
system, component or separate technical unit which is the subject of the approval process .  
3.27 Registered Laboratory:  
A laboratory accredited based on ISO 17025 by an approved body in the field of industry 
testing fo r trailers and semi -trailers. This lab is  registered by SASO in order to approve the 
reports issued by it i n the procedures of licensing a Logo usage.  
3.28 Test Report:  
 A test report iss ued by a registered laboratory,  provided that the date of issuance does not 
exceed one year at the time of applying for the license.  
   
 
   
   
 
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 SASO STANDAR D  SASO 31259 :0000  
  4   DIMENSIONS  
4.1 All dimensions shal l be determined with the trailer  at its unladen mass.  
4.2 None of the outward -opening windows or ventilators and wing mirrors shall protrude by 
more  than 300 mm outward  from the outermost point on both sides, of the vehicle, and by  
more than 300 mm upward fr om the highest top point of the vehicle. In the case of rear -wing 
mirrors attached to a tractor towing a trailer with a width exceeding that of the tractor, a 
protrusion of these mirror s not exceeding 300 mm form t he outer most point on both sides of 
the trailer may be allowed.  
4.3 The vehicle length sh all be the distance between two v ertical planes perpendicular to the 
longitudinal median  plane and touching the front and rear of the vehicle  respectively and it 
shall not exceed 20m for trucks and trailer s, 18m  or 23m for tractor and semi -trailers,  23 m 
for articulated vehicles.  
4.4 The vehicle width shall be the distance between two planes parallel to the  longitudinal 
median plane and touching the vehicle on either side of the said plane  and it shall not exceed 
2.6m.  
4.4.1 All part of the vehicle including  any lateral projecting of fixed parts (wheel hubs, door  
handles,  bumpers,  etc.) are contained between these two planes.  
4.5 The height of the  vehicl e shall be the distance between the supporting surfaces and  the 
horizontal plane touching the topmost part  of the vehicle and it shall not exceed 4.5 m.  
4.5.1 When measuring the vehicle  structural height all fixed parts of  the vehicle is contained 
between these two planes.             
 4.6 For  vehicles with dimensions exceeding th e limits given in  standard and which are 
necessarily needed for  use, an approval  from the authorities responsible for  transportation 
shall be attained prior to their clearance and use  on roads.  
FOR D ETAILED REQUIREMENTS FOR DIMENSION  REFER TO SASO 469, SASO 
GSO 42 AND SASO ISO 612.  
 
 
   
   
 
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 SASO STANDAR D  SASO 31259 :0000  
5. MINIMUM ROAD CLEARANCE    
5.1 Any part other than the ear th-touching parts of a vehicle  shall have adequate clear ance 
above the ground so as to ensure safe driving.  
5.2 The clearance shall be such that any rigid parts of the vehicle should not touch the level 
ground and get damaged due to  impact.  
5.3 Due to design constriction any projecting parts should be  provided with guards to avoid 
the rigid part being affected for safety reasons.  
 
6. GROSS VEHICLE AND AXLE WEIGHT  
 
6.1   The Gross  Vehicle  Weight is the maximum weight of the fully  laden vehicle, based on 
its construction and design performances, as declared by the manufacturer. This shall be less 
than or equal to the sum of the maximum axles capacity. The  gross vehicle weight shall not 
exceed 45 tones.  
6.2 The  Unladen Vehicle weight  shall be determined by the following criteria:  
6.2.1 Weight  of the vehicle with bodywork and all  factory fitted equipment, electrical and  
auxiliary equipment for normal operation  of vehicle, including liquids, tools, fire  
extinguisher, standard  spare  parts, chocks and spare wheel,  if fitte d.  
6.2.2  The fuel tank  shall be filled to at least 90% of rated  capacity and the  other liquid 
containing  systems to 100% of  the capacity specified by the manufacturer.  
6.3 The design and weight carrying capacity of the axles shall be  suitable to the gross axle 
weights allowed by the manufacturer.  
6.4 The trucks/tractor with trailer fully loaded shall be capable of  ascending not less than 15% 
grade ability.  
6.5 Front supports of semi -trailers (standing legs) and lifting  gears shall be capable of 
supporting the semi -trailers fully  loaded plus 10% in excess of load.  
6.6 For  vehicles with weight exceeding the limits given in standard  and which are necessarily 
needed for use, an approval from the  authorities responsible for transportation shall be 
attained prior  to their clearance and use on roads.    
   
 
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 SASO STANDAR D  SASO 31259 :0000  
6.7   Maximum axle weights  
6.7.1 Maximum  axle (s) capacity of a vehicle is the permissible weight corresponding to the 
maximum weight to be carried by the axle (s) as defined by th e vehicle manufacturer, not 
exceeding the axle manufacturer’s specifications. The  maximum axle(s) capacity shall be less 
than or equal to the sum of the maximum capacities of the tyres. 
6.7.2 In the case of tandem axles the total weight on the tandem axles  shall be in  depend on 
the distance between the two rears  axles or the distance between the first and the third rear 
axles.  
 
FOR DETAILED REQUIREMENTS FOR WEIGHTS REFER  TO SASO 469  AND SASO GSO 42 . 
 
7. STABILITY  
7.1 The trailer  should not pull to left or right during driving.  
7.2 Any  vehicle in the u nladen and laden state shall not overturn when tilted to the left or 
right side at an angle  specified  in the re gulation (35  ̊ ) or the rollover stability of the shall be 
such the poi nt at which overturning occurs  should be limited  to the lateral acceleration.   
7.3 MANEUVERABILITY  REQUIREMENTS  
7.3.1 Any motor vehicle and any semi -trailer must be able to  maneuver  on either side for a 
complete circular trajectory of 360° inside an area defined by two concentric circles, the  outer  
circle having a ra dius of 12. 50 m and the inner circle having a  radius of 5. 30 m, without any 
of the vehicle's  outermost points  (with the exception of the protruding parts  prescribed for the  
vehicle width in a paragraph 4.4) projecting  outside the  circumferences of  the circles .  
7.4 Tractor - trailer combination shall comply with the  maneuverability  requirements, as laid 
with Figure  (3).                                                                                                                        
7.5 The location of the center  of gravity (CG) of a road vehicle, as  defined in ISO 3833.  A 
method for determining the coordinates of the CG in the horizontal plane is provided. Two 
methods for determining  the height of the CG above the ground are specified . The axle lift 
and the stable pendulum methods are the most common  methods for determining vehicle CG 
heigh t.    
   
 
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 SASO STANDAR D  SASO 31259 :0000  
7.6 Tipper  trailer fully loaded shall not overturn during  discharging when the tipper body 
reach the highest position.  
FOR MORE DETAILED REQU IREMENTS FOR STABILITY REFER TO  SASO GSO 42 , 
SASO ISO 8855  AND, SASO ISO 10392 . 
8.  ELECTRIC SYSTEM  
8.1 The electric supply system shall be such that it is suitable (Ah)  to the vehicle  capacity, 
fixed firmly, provided with suitable fuses, the current supply without any overheating, which 
may result  in fire.  
8.2 The resistance between all exposed conductive parts and the electrical chassis shall be 
lower than 0.1ohms when there is current flow  of at least 0.2amps in the case of hybrid 
vehicles . 
8.3 The electrical cables provided shall be suitable for the current carrying capacity and 
additionally protected to avoid any leak of current.  
8.4 The trailer  with batteries at the rear shall be provided with additional safety cut off 
devices near the batter y to cutoff the supply in case of an impact and the current supply cable 
severed.  
8.5 Electrical parts should be provided with a protection enclosure  against access  external 
influences , foreign objects and/or water . 
8.6 The electric wiring on the outside of the body, or in any part  of the trailer vehicle 
containing dangerous materials, shall be  protected by an electrically insulated cover resistant 
to fire  and firmly fixed to the vehicle body. The size of conductors  shall be large enough to 
avoid overheati ng. Circuits shall be  protected by fuses or automatic circuit breakers.  
8.7 The battery terminals shall be electrically insulated or  covered by the insulating battery 
box cover. They  shall be  fitted in a vented box.  
8.8 Lamp bulbs with screw cap shall not be used.  
8.9 A switch for breaking the electrical circuits shall be placed as  close  to the battery as 
practicable.    
   
 
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 SASO STANDAR D  SASO 31259 :0000  
FOR DETAILED REQUIREMENTS ON ELECTRIC SYSTEM  REFER  TO SASO  GSO 42 
AND  SASO  ISO 20653.  
 
 
9. BRAKING SYSTEM  
 
9.1 The br aking system provided  to the trailer  shall be suitable to the vehicle concern and 
ensure safe braking performance under normal and emergency conditions.  
9.2 Every  trailer shall be equipped with service brake system adequate to control the 
movement of, and to halt it safely, speedily and effectively whatever its speed and load, on 
any up or down gradient.  
9.3 The secondary braking system is required and shall make it possib le to halt the vehicle 
within a  reasonable distance in the event of failure of the service braking system.  
9.4 No material affecting the public health, directly or after reaction with other  components 
such as asbestos and cadmium, shall be used in the brak e system.  
9.5 The control of the service braking device shall be independent of the control of the  
parking braking device.  
9.6 Brake pipes shall be so attached to the chassis or equivalent that they are not  
unnecessarily subjected to damage through vibration or abrasion and shall be  made of 
materials resistant to corrosion or treated by any process which ensures  such resistance.  
9.7 The parking braking system shall make it possible to hold the  vehicle stationary on  an up 
or down gradient of 18% even in the  absence of the driver, the working parts  being then held 
in locked  position by a purely mechanical device. In the case of  vehicles  with trailers, the 
gradient will be 12%.  
9.8 The trailers  category O3,  O4 shall be provided with Anti-lock braking system (ABS).  
9.9 The connections of the compressed -air braking systems between  power -driven  vehicles 
and trailers shall be provided acc ording to choose one of the follow ing: 
9.9.1 One pneumatic supply line and one pneumatic control line . 
9.9.2 One pneumatic supply line, one pneumatic control line and one  electric control line .   
   
 
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 SASO STANDAR D  SASO 31259 :0000  
9.9.3 One pneumatic supply line and one electric control line . 
The SASO REGULATION ON BRA KE IS UNDER PREPARATION UNTIL SUCH TIME 
VEHICLES SHOULD COMPLY WITH REQUIREMENTS OF  BRAK E OF ECE  OR 
FMVSS REG ULATIONS.  
 
FOR DETAILED REQUIREMENTS ON BRAKING SYSTEM  REFER TO SASO GSO 42 
AND  ECE 13.  
 
10. SUSPENSION SYSTEM  
 
10.1 Depending on the category of vehicle the suspension provided  shall be suitable  to reduce 
the shocks to the vehicle  from  the uneven level of the  road, to reduce the load transmitted 
from the  vehicle to  road surface and damage the road surface and to drive  the vehicle  safely.  
10.2 Every trailer  vehicle shall be equipped with springs and shock absorber or any  other 
shock  absorbing system which has  adequate capacity depending on the  GVW of the vehicle, 
against the impact from the ground and can ensure safe  driving on uneven and rough road.  
10.3 The suspension system provided for trailer  used in construction  sites shall be  suitable to 
carry the maximum load applied and the  rough terrain in which they are  used. 
10.4 The durability of the suspension system should be tested by  carrying out durability  tests 
in accordance with the relevant  international and manufacturer's  specifi cations.  
 
11. FRAME AND BODY  
 
11.1 The frame and body shall be so secure and strong enough as to  fully withstand the  
operat ion of the trailer . 
11.2 The chassis  shall be strong enough to carry the maximum load  applied to the  trailer  in 
use. 
11.3 The floor ing in all trailers  shall be substantially constructed  in good conditions according 
to purpose used.  
11.4 The trailers and its body shall be suitable with respect to the GCC terrain, operating 
conditions and c limatic conditions prevailing in GCC count ries.   
   
 
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 SASO STANDAR D  SASO 31259 :0000  
11.5 Trailers shall be mounted with rear  and side shields  (rear and side  under - run protections) 
to protect against  under running of  vehicles in the event of  rear or side collision.  
11.6 All vehicles carrying goods , including tankers, mobile cranes,  mobile workshops, traile rs 
and semi -trailers of maximum mass exceeding 3.5 tones sh all be equipped with rear under run 
protective devices to p rotect against under running of vehicles in the event of rear collision  
with passenger cars,  multi -purpose vehicl es and light duty trucks having a  maximum mass not 
exceeding 3.5 tones.  
11.6.1 The maximum mass of a trailer type for which the rear underrun protective device t o 
be installed shall not exceed the value indicated on the rear underrun protective device for 
which it is designed for.  
11.6.2 The rear under run protective d evice to be installed to the trailer shall be suitable to the 
trailer to prevent under running of light duty vehicles . Its surface shall be made of a reflective 
type.  
11.7 Lateral protection f ix to all  vehicles ca rrying goods, including tankers mobile cranes,  
mobile workshops, traile rs and semi -trailers of maximum mass exceeding 3.5 tones shall be 
constructed and equipped in such a way as to offer, throughout their length, at both  sides 
effecti ve protection to unprotected road users against  the risk of falling under  the sides of the 
vehicle and being  caught under the wheels.  
11.7.1 Components  permanently f ixed to the trailer, e.g. spare wheels, battery box, air tanks , 
fuel tanks, lamps, reflectors and tool boxes may be inco rporated in the guard, provided that 
they meet the d imensional requirements of this Regulation. The requirements of items from 
4.2.5 to 4.2.8 at SASO GSO 2113 shall generall y apply as regards gaps b etween protective 
devices and  permanently fixed components.  
11.7.2 The outer surface of the LPD shall be smooth, and so far, as possible continuous from 
front  to rear and its surface shall be made of a reflective type.  
11.7.3 Lateral Protection Device (LPD)  shall be essentially rigid and shall be mounted 
securely without any vibration in normal use of the vehicle. It shal l be made of metal or any 
other suitable material.       
   
 
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 SASO STANDAR D  SASO 31259 :0000  
11.8 Spray -suppression devices mu st be constructed in such a way  that they operate properly 
when used normally on wet roads.  Moreover , the automotive trailer manufacturing they must 
incorporate no structural or def ect detrimental to their proper functioning or behavior . 
11.9 Every trailer vehicle used for t ransporting dangerous materials  shall carry markings 
indicating the natur e of the load and the class of hazard in accordance with the relevant SASO  
standard.  
11.10 for tankers carrying fuel and equipped with auxiliary equipment “e.g. pumps” it should 
be constructed in  compliance with NFPA 385 chapter 8  (NATIONAL FIRE PROTECTION 
ASSOCIATION) . 
Note : Tanker shell shall be made from aluminum alloys with shiny bright finish.  
 
Note : It will be stopped working for tankers constructe d from steel by the end of 2020 and should be 
replaced by tanks manufactured from Aluminum material.  
FOR DETAILED RE QUIREMENTS ON VEHICLES CARRYING DANGEROUS GOODS 
REFER TO SASO REGULATIO NS SASO 1285,  SASO  1286,  SASO 1287, 1288 AND 
SASO 2288. 
11.11 The rear of the trailers  shall be provided with  designated location  sufficient in size to 
fix the number plates  made in  accordance with the SASO  technical regulation No. SASO 572 . 
11.12 Requirements for windows and partitions Transparent partitions and windows fitted 
to any trailer shall be:  
a) of safety glass that complies with the relevant requirements given in SASO  ISO 3536  
standard  or any a lternative regulation . 
b) of plastics safety glazing material that complies with the relevant requirements in SASO 
ISO 15082  standard  or any alternative regulation . 
FOR DETAILED REQUIREMENTS ON FRAME AND BODY REFER  TO SASO 572 
AND SASO GSO  42, 2113, 2114  AND SASO ISO 3 536, 15082 . 
 
12. COUPLING DEVICES AND TOWING METHODS  
12.1 When two or more vehicles are operated in combination, the  coupling devices  
connecting the vehicles shall be designed, constructed  and installed, and the  vehicles shall be   
   
 
16 
 SASO STANDAR D  SASO 31259 :0000  
designed and  constructed so that when the combination is  operated in a  straight  line on a 
level,  smooth,  paved surface, the path of the  towed  vehicle will not deviate more than  76 mm 
to either side of the  path of the towing  vehicle.  
12.2 All characteristics necessary for the m ounting and interchangeability of drawbar couplings 
on the frame (cross member, draw beam  or mounting bracket) of towing vehicles for trailers 
according to the ISO 3584.  
12.3 The manufacturer  must lay down the dimensions necessary  for the compatibility of  
mechanical coupling devices between light trailers or caravans and towing vehicles, when the 
latter are  fitted with a coupling ball.                       
12.4 The maximum allowable wear an d the limit dimensions of worn components of in -use 
mechanical c ouplings, will ensure the safe operation on the road of heavy comme rcial vehicles 
fitted with such couplings.  
12.4 Every fifth wheel assembly shall have a locking mechanism. The  locking  mechanism 
and any adapter used in conjunction with it shall prevent separation of  the upper and lower 
halves of the  fifth wheel assembly unless a positive manual  release is activated.  
12.5 The fifth wheel coupling pin which is used fo r coupling semi -trailers to prime movers, it 
should be taking  into account the limitations  of weight generally laid down by official 
requirements.  
12.6 The fifth wheel kingpin shall be equipped with all the fixtures needed to attach it to the 
vehicle (see ISO 337 and ISO 4086 ). The  method of mounting shall be identical to that 
subsequently employed on the vehicle itself.   
12.7 Electrical connectors that are fitted for the purpose of towing and towed  vehicles should be 
complying with 12 v sys tems or 24 v systems according to the trai lers category applicable. Refer  
to SASO ISO 1185 , 1724, 3731,4091,11446 , 12098 or alternative connectors.  
12.8 The location for the electrical connect ion of the braking systems and running gear of towing and 
towed vehi cles with 12  v AND 24  v nominal supply  voltage and park socket used to receive and store 
the plug when disconnected according to ISO 4009  standard  or any alternative regulation .    
   
 
17 
 SASO STANDAR D  SASO 31259 :0000  
12.9 The locations of coupling devices for elect rical and pneumatic connections between towing and 
towed commercial  road vehicles. It is applicable to heavy vehicles equipped with pneumatic braking 
systems and 24 V e lectrical equipment of the following types: draw bar-trailer combinations whose 
towing vehicles have rear -mounted couplin gs or couplings mounted forward and below, and 
articulated vehicles according to standard . 
FOR DETAILED REQUIREME NTS COUPLING DEVICES AND TOWING METHODS 
REFER TO SASO ISO 337 , 1103,1726,3584,3842,4086,7638,8716 , AND TS 20825 . 
 
13. WHEELS (T YRE S AND RIMS)  
 
13.1 Tyre/wheel combination recommended by the manufacturer should suitable and indicate 
size designation,  load-capacity index,  speed  category symbol, rollin g resistance in accordance 
with accepted SASO  standard.  
13.2 The tyres shall withstand endurance test, high speed performance  test, Bead  unseating 
tests, Strength tests, Temperature resistance  tests, rolling  resistance and  wet grip tests 
specified in ECE 117.  
13.3 Retreaded tyres shall display o n both sidewalls in the case of symmetrical tyres and at 
least on th e outer sidewall in the case of asymmetrical tyres. 
13.4 The retreaded pneumatic tyre accepted for trailer category O3, O4. 
13.5 The trailer s shall be provided with  spare tyre.  
FOR DETAILED REQUIREMENTS ON WHEELS  REFER TO SASO  REGULATIONS 
SASO 1134 , 1135,1136,1275,1771 , AND  SASO GSO ECE 117  AND SASO ISO 4107.  
 
14. LIGHTING EQUIPMENT  
14.1 General  
14.1.2 The lighting equipment shall be so fitted that under no rmal conditions of use and 
notwithstanding any vibrations to which  they may be subjected in such  use their  satisfactory 
operation  remains assured  and they retain the photometric  characteristics prescribed in SASO  
GSO 42 standard.    
   
 
18 
 SASO STANDAR D  SASO 31259 :0000  
14.1.3 Lighting equipment mounted in pairs sh all be of the same  colorimetric requirements 
and symmetrically appropriate  photometric characteristics.  
        14.2 A summary of the requirements for each type of lamp and  reflector is given in the 
following table .          
 
Description color Location  of 
emitted light Item  
- Clearly visible even in day time 
from a distance to be clearly 
identified by the vehicles coming 
behind to avoid any rear impact .  
- should be actuated upon 
application of the service brake .  Red color  Each side at 
the Rear Stop lamp (brake lamp) 01 
- Clearly visible at night at a  
suitable distance to the rear to 
avoid any rear impact .  
- shall be wired so that it will 
light simultaneously on both 
sides with the front position 
lamps .  Red color  Each side at 
least one at 
the rear Rear position lamp        02  
Its optional for category  O1.  -  
  - The intensity of the reversing 
lamp shall be not greater than 5000 
candles .  
- give a clear vision to rear when 
reversing .  
- for the all vehicle with length 
exceeding 6,000 mm, two devices 
mandatory and two devices 
optional .  White 
color Not more 
than two  
lamps at the 
rear Reversing lamp      03 
- The intensity of the direction 
indicator lamps shall be such that 
it will be visible from any height 
not more than 2.5 meters above the 
ground at a safe distance to the 
rear. 
- Front and rear direction indicator  
lamps shall, when in operation, be 
visible, even in d aytime.  
The direction indicator lamps may 
be so designed and constructed 
that they also act as the hazard 
warning flashing lamps.  Amber/red 
color Two mounted 
on the  rear 
 Direction Indicator Lamp     04   
   
 
19 
 SASO STANDAR D  SASO 31259 :0000  
- The signal shall be given by 
simultaneous operation of the 
direction indicator lamps.  
- Hazard warning flashing lamps 
shall comply with the  requirements 
of direction indicator lamps . 
- if a power -driven vehicle is 
equipped to draw a trailer the 
hazard warning signal control shall 
also be capable of bringing the 
direction -indicator lamps on the 
trailer into action.  
- hazard warning signal shall be 
able to function even if the device 
which starts or stops the engine is 
in a position which makes it 
impossi ble to start the engine.  
 Amber/red 
color Two mounted 
on the rear  
 Hazard warning flashing 
lamp     05 
- Equipped for trailer,  semi -
trailers if width exceeding 2.1 m .  
- it should be mounted so as 
indicate the extreme width on the 
trailer vehicle .  
- The intensity of the clearance 
lamp shall be clearly visible night 
at a sufficient distance to avoid 
any accident by other vehicles .  Front 
display  an 
amber or 
white 
color .  
Rear 
should be 
amber or 
red color .  Each side one  
at the front 
and rear Clearance lamp     06 
- Any vehicle exceeding 6m in 
length shall be equipped with front 
and rear side marker lamps or side 
reflectors on both sides of 
vehicles.  
- The side marker lamps shall be 
clearly visible at night at a suitable 
distance from the side of the 
vehicle to avoid any accidents.  Front and 
center 
amber 
color  and 
the rear 
Red or 
amber 
color 
 front and rear 
side marker 
lamps 
 
 
 
 
 Side marker lamps 
 
 
And    07 
- The side reflectors shall be 
clearly visible at night at a 
sufficient distance from the side of 
the vehicle to avoid any accident 
when illuminated by head lamp 
beams.  
 Front and 
center 
reflect 
amber 
color  and 
the rear 
reflect 
Red or 
amber 
color 
 On both sides 
of vehicle for 
side reflectors side reflector 0   07.1  
- making it clearly visible from a 
distance of 20 meters to the rear.  White 
color In the rear 
registration 
number plate Rear registration plate 
lamp    08   
   
 
20 
 SASO STANDAR D  SASO 31259 :0000  
- The registration plate lamp shall 
be wired so that it is on when the 
head lamps and front and rear 
position lamps are on.  
 
- The re ar fog lamp is optional 
provided if the intensity of the rear 
lamps complies  with the SASO 
regulation.  Red color  A minimum 
one in the 
rear Rear fog lamp    09 
                
 
FOR DETAILED REQUIREMENTS ON LIGHTING EQUIPMENT  REFER TO SASO ISO 
303. SASO GSO  42, SASO GSO ECE 48  AND  SASO ISO 13207 . 
 
15. INCOMPLETE VEHICLES  
15.1 The incomplete trailer vehicles shall be completed in  accordance  with the technical  
information and instructions  supplied by the  incomplete vehicle manufacturer.  
15.2 The manufacturer shall supply the following information:  
15.2.1 The gross vehicle weight rating of the completed trailer vehicle  for which the incomplete  
vehicle is manufactured.  
15.2.2 Gross axle weight rating for each axle of the completed trailer vehicle.  
15.2.3 A compl ete manual containing a technical instruction for completing the trailer vehicle  
for its intended purpose.  
15.3 The final stage manufacturer shall complete the trailer vehicle in  accordance with the  
instructions supplied by the incomplete  trailer vehicle manufacturer.  
15.4 A label shall be affixed by the final stage manufacture in  accordance with the  relevant 
SASO  regulation.  
FOR DETAILED REQUIREMENTS ON VEHICLES MANUFACTURED  IN MULTI 
STAGE REFER TO SASO  REGULATIO (SASO 703) . 
 
 
 
   
   
 
21 
 SASO STANDAR D  SASO 31259 :0000  
 
  16. VEHI CLE IDENTIFICATION NUMBER (VIN)  
16.1 GENERAL REQUIREMENTS  
Each manufacturer trailer should have Identification number (VIN) assigned by the 
manufacturer according to SASO standard SASO -2249.                             
16.1.2 Each trailer manufactured in one s tage shall have a VIN assigned by the manufacturer.  
16.1.3 Each trailer manufactured in more than one stage shall have a VIN assigned by the 
incomplete vehicle manufacturer.  
16.1.4 Each VIN shall consist of seventeen (17) characters.  
16.1.5 The check digi t shall appear in position nine (9) of the VIN.  
16.1.6 The VINs of any two vehicles manufactured within a 30 -year period shall not be 
identical.  
16.1.7 Only the following Arabic numerals and capital roman letters shall be used in the VIN:  
0123456789.  
ABCD EFGHJKLMNPRSTUVWXYZ.  
16.1.8 The VIN content shall consist of four (4) sections.  
16.1.9 The VIN location shall be readable from outside according to SASO 2251 paragraph 
4.1.2.  
16.1.10 Each vehicle must have its own special number engraved or engraved on th e internal 
frame structure or on any other similar body, on the left side of the vehicle, as determined by 
the manufacturer.  
                            See table 1 & 2 for sample deciphering submission.  
FOR DETAILED REQUIREMENTS FOR VEHICLE IDENIFICATION  NUMBER (VIN) 
REFER TO SASO 2249, SASO 2250, AND SASO 2251.    
   
 
22 
 SASO STANDAR D  SASO 31259 :0000  
TABLE 1 
 Placement of information in manufacturers vin 
                                         section th4  rd3
section                    section nd2               section st1 Section     title 
vehicle indicator section (VIS) 
- Number sequentially assigned In 
positions 12 -17 if a high - vol. min . or  
In positions  15-17 if a low -vol.  
Manufacture .   - Plant   Model 
year    Check 
digit   Vehicle description 
(VDS )  World manufacturing 
identify (WMI)           
17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 CHARACTER 
OR 
POSITION       
N 
 N N N B B B B B B B B B B B B B Type (character)  
 
 
 
A= Alphabetic 
N= Numerical 
B= Alphabetic or       
Numerical         
 
Sequential  production  number 
 
  
 Location 
of plant 
that 
affixes  
v I n Model  
year 
 
 
H=2017 
J=2018 
K=2019 
L=2020 
M=2021 
   Check  
digit 
 
Refer to 
SASO 
2249 
Para.4.1.5   
Describe :    
  Trailer  type.           
  Body  type.  
  Length .   
  Number  of axles .    
 
   For sample deciphering 
see table 2.     
           Defined by of  
SASO 2250  
first & second position is an 
alphabetic or numeric 
character assigned from 
international agency (SAE).  
Third position is assigned by 
national organization or 
partner and is consisting of 
an alphabetic character from 
A to Z (I, O & Q are 
excluded) or numeric 
character from 1 -8 (9 is 
reserved for production of 
less than 500 vehicles /year)   
If manufacture                   sequential 
Produces less than            production 
500 vehicles in                    number  
A year                                                        
   
 
23 
 SASO STANDAR D  SASO 31259 :0000  
 
TABLE  2  
VIN SAMPLE DECIPHERING SUBMISSION  
 
Vin deciphering 
 Vin deciphering submission  
  section ST1 
Assigned by 
international agency   
SAE     WMI Position 1    
Assigned by 
international agency   
SAE     WMI Position 2    
Assigned by national 
organization or partner     WMI Position 3  *  
  ** section nd2 
1= Ball type pull 
2= Pintle hitch 
3= Gooseneck 
4= Straight semi 
5= Fifth wheel 
6= Kingpin Type of trailer 
For all trailer type the make 
is Position 4 
A = Snowmobile trailer   
B = Boat trailer 
C = Car hauler trailer 
D = Dump trailer 
E = Enclosed trailer  
F = Flatbed trailer 
G = Curtain side trailer 
H = Hydraulic dovetail   
J = Double drop trailer 
K = Camper trailer 
L = Lowboy trailer 
M = Motorcycle trailer 
N = Livestock trailer 
P = Pole trailer 
R = Reel trailer 
S = Stacker trailer 
T = Tank trailer  
U = Utility trailer 
V = Straw trailer 
W = Landscape trailer 
X = Logging trailer 
Y = Satellite trailer 
Z = Converter dolly Body type Position 5 
6= 6 feet long  length Position 6   
   
 
24 
 SASO STANDAR D  SASO 31259 :0000  
9= 9 feet long  
A= 26 feet long 
A= Aluminum 
B= Stainless steel 
C= Carbon steel   
D= Fiberglass/composite 
E= Type of material Position 7 
1= Single Axle 
2= 2 Axles  
3= 3 AXLES  Number of axles Position 8 
  section rd3 
Must Calculate for each 
VIN refer to SASO 2249 
para.4.1.5 Check digit Position 9 
  section th4 
Per regulation :  
H = 2017 
 J = 2018 
 K = 2019 
 L = 2020 
 M = 2021 
 N = 2022 
 P = 2023 
 R = 2024 
 S = 2025 
 T = 2026 
 V = 2027 
 W = 2028 
   X = 2029  
  Y = 2030 , etc.    Model year Position 10 
R = RIYHAD 
J = JEEDAH 
D = DAMMAM Plant location Position 11 
Assigned by national 
organization or partner     WMI Position 12  *  
Assigned by national 
organization or partner     WMI Position 13  *  
Assigned by national 
organization or partner     WMI Position 14  *  
001, 002, 003, ETC ….  
The first vehicle of any 
model year will be 
001.the second will be 
002. And so  ….  Sequentially assigned 
number Position 15.16. and 17 
 
    * =     IF A MANUFACTURE PRODUCES LESS THAN 500 VEHICLES IN A YEAR  the WMI is assigned 
by international agency SAE .    
     ** =   The layouts s hown in table 2 as attributes i s given as deciphering submission examples  only and are not 
restrictive .     
   
 
25 
 SASO STANDAR D  SASO 31259 :0000  
17. COMPLIANCE PLATE  
 
17.1 Every applicable trailer shall bear an Approved Compliance  Plate which shall be placed in a 
conspicuous position on the  trailer.  
17.2 The manufacturer shall affix, on the chassis of the trailer, a label  meeting the following 
requirements:  
17.2.1 It shall be made of material resistant to deterioration.  
17.2.2 The label shall, unless riveted, be pe rmanently affixed in such a manner that it cannot be 
removed without being destroyed.  
17.2.3 The following information shall be written (in Arabic or English  language) in letters at least 
2.4 mm high and in a clearly legible  manner:  
17.2.3.1  Name of manufa cturer and country of manufacture (or assemble).  
17.2.3.2 Year and month of production.  
17.2.3.3 Maximum (gross) vehicle weight (GVW) in kilograms.  
17.2.3.4 Maximum (gross) axle weight (GAW) for each axle, in kilograms.  
17.2.3.5 The trailer identification  number.  
17.2.3.6 The category of trailer.  
17.2.3.7 The statement “This trailer conforms to all applicable SASO  standard and Technical 
Regulations in effect up to the date of  manufacture ” referred to table  - 3. 
17.2.4 Additional information may be included  at the discretion of the  Manufacturer.  
17.2.5 In the case all of the information required by  manufacturer is  contained in the ‘Compliance 
Plate’  a separate vehicle plates need not be fitted.  
FOR DETAILED REQUIREMENTS ON COMPLIANCE PLATE REFER TOSASO 
REGULATIONS SASO 400 AND SASO GSO 42.  
 
                                
   
 
26 
 SASO STANDAR D  SASO 31259 :0000  
 
 
 
 
Fig-1 & Fig -2  
For brake and electrical connections locations 
  
   
 
27 
 SASO STANDAR D  SASO 31259 :0000  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fig.3 Vehicle maneuverability  
                                              
R= 12.5 m  
U = max. 1.2 m  
Rb = min. 5.3 m  
 
   
   
 
28 
 SASO STANDAR D  SASO 31259 :0000  
 
 
 
TABLE – 3 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
   
 
29 
 SASO STANDAR D  SASO 31259 :0000  
REFERENCE 
 
 
 
 
Uniform provisions concerning the approval of vehicles of 
categories M, N and O with regard to braking . ECE 13  
Commercial vehicles — Location of electrical  and 
pneumatic connections between towing vehicles and trailers . ISO 4009