Elaine Boys, from Horsham, was travelling northbound on the dual carriageway with her 15-year-old son when she was forced to swerve out of the way of the oncoming object near Dial Post.
She had a split second to reacted and the wheel whisked beyond her car and into a grey Volkswagen Golf behind.
Elaine said she was very lucky not to be hit and has pleaded for people to make sure they stay alert when driving.
She said: “It was probably one of the most scary experiences I think I have come across on the road.”
The incident took place just after 11am on Monday (August 20).
Elaine said as she passed the speed camera near Dial Post she saw a queue of traffic in the southbound carriageway.
“One of the cars further back in the group of vehicles was flashing its lights,” she said.
“Literally a split second later a tyre came flying across the carriageway in the path of my car. I swerved and God knows how it missed me.”
Elaine was driving her convertible and said she heard a ‘crunch’ behind her.
“Having seen it in my rear view mirror it wrecked the car behind me.
“I had my 15-year-old son in the passenger seat. He was quite freaked out about it all.”
Two fire engines had been driving past at the time and stopped at the scene.
Police were also called and said the driver of the Golf - a 62-year-old woman from Worthing - was not injured.
Elaine drove back round to the scene to check everyone was okay.
“I just needed to get back and make sure the person was okay,” she said.
“She had obviously been saved by the car and the airbag in the car.”
The wheel had become detached from a blue tipper lorry, being driven by a 67-year-old man from Henfield, as it travelled southbound along the A24.
Elaine said it was not something she ever expected to come across on the road and said it was a reminder to everyone to always stay alert when driving.
“It was just only a split second thing it was so quick, so fast and luckily my instincts made me swerve. I could have swerved into a car,” she said.
“Obviously my guardian angel was looking out for me.”