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2011 rule changes - doubled wheel tethers 03 February 2011

In a bid to further reduce the chances of wheels coming loose - and potentially impacting a driver's head - in the event of an accident, the 2011 regulations require four tethers at each corner of the car, double the 2010 requirement. The tethers are bigger, stiffer, and have to pass a more severe load test.

FIA Technical Regulation
10.3.6 - In order to help prevent a wheel becoming separated in the event of all suspension members connecting it to the car failing provision must be made to accommodate flexible tethers, each with a cross sectional area greater than 110mm². The sole purpose of the tethers is to prevent a wheel becoming separated from the car, they should perform no other function.
The tethers and their attachments must also be designed in order to help prevent a wheel making contact with the driver's head during an accident.
Each wheel must be fitted with two tethers each of which exceed the requirements of 3.1.1 of TestProcedure 03/07.
Each tether must have its own separate attachments at both ends which :
- are able to withstand a tensile force of 70kN in any direction within a cone of 45° (included angle) measured from the load line of the relevant suspension member ;
- on the survival cell or gearbox are separated by at least 100mm measured between the centres of the two attachment points ;
- on each wheel/upright assembly are located on opposite sides of the vertical and horizontal wheel centre lines and are separated by at least 100mm measured between the centres of the two attachment points ;
- are able to accommodate tether end fittings with a minimum inside diameter of 15mm.Furthermore, no suspension member may contain more than one tether.
Each tether must exceed 450mm in length and must utilise end fittings which result in a tether bend radius greater than 7.5mm.