F1 is moving to reduce the risk posed by flying wheels.

F1 is moving to reduce the risk posed by flying wheels.

Last year, GP2 driver Henry Surtees died when a stray wheel from a crashed car struck him on the head.

There was a similar incident during the final practice session at Hockenheim last weekend, with Timo Glock narrowly avoiding a bouncing wheel after Vitantonio Liuzzi's crash.

"I was lucky that I left a bit of room behind Liuzzi in the Motodrom to warm up my brakes. Otherwise I would have been right behind him," the German told Auto Motor und Sport.

A tether on Fernando Alonso's Ferrari broke in his Monaco crash this year.

F1 introduced wheel tethers in 1998, connecting the wheels to the chassis. They are made of a special polymer called polybenzoaoxide or Zylon.

But flying wheels continue to pose a risk to drivers as well as to spectators, as seen in Melbourne in 2001 with the death of a marshal behind the spectator fencing, and in 2000 when a marshal was killed at Monza.

"Tethers are of great concern to us," said McLaren's engineering director Paddy Lowe.

"We discussed the issue at the Technical Working Group and we have agreed for next year to introduce a second tether on every corner," he revealed to reporters during a teleconference.

Gallery: F1 moves to stop wheels flying after crashes