Tether Cars are model racing cars powered by miniature internal combustion engines and tethered to a central post. Unlike radio control cars, the driver has no remote control over the model's speed or steering.
A model race car must have four wheels and must be powered by a combustion engine (piston engine). The power must be transmitted to one or more wheels directly or by means of a gear box. The contact points of the wheels with the surface are to form angles of a rectangle or a trapezium. Wheels on the same axle, ie front or rear, must have the same nominal diameter. However it is not necessary that the front wheels be rotated against each other. In disassembled condition two independent wheels must exist.
Important load carrying and power transmitting items for example, like the bottom pan, bridle, engine and wheel mountings, axles etc. must be calculated to dimensions, that they can stand the loads during the run with an adequate factor of safety.
Every car must have a top cover, which together with the chassis must form a body which covers all parts with the exception of the following: cylinder head, pipe including fixing bracket, shut off lever, vent pipes to tank, needle for needle valve, bridle, tail skid and wheels. The bodywork must be designed, so that the car can be shut off without any risk of damage. At international races the body of every car must carry a national identification mark and a national identification number, with letters at least 20 mm in height.
Every car must have a bridle for attachment of the cable made of material with a minimum tensile strength of 500 N/mm2. The bridle must be designed to have minimum dimensions.
Additional connectors between bridle and cable connector and cable and centre arm are not allowed. All bridles must have a coloured mark at the outer end adjacent to the connector hole, approximately 20 mm in width (paint or tape). The colour shall match the colour of the tether cable for the respective class. (E-1 White, E-2 Green, E-3 Yellow, E-4 Red, E-5 Black)
The following race-classes are mandatory:
Maximum allowable deviation for all classes: 0,009 cm3, measuring point = Upper dead centre.
A ready to run car, including all items carried like fuel and battery must not exceed the weight listed below: