A Gravenhurst man has been seriously injured after his pickup truck was hit by a flying tire.

Provincial police say the crash happened at 12:40 p.m. on Friday on Highway 11, just north of Southwood Road. The wheel came off of a pickup truck that was headed south on the highway.

“The wheel came across the median and struck the northbound vehicle square in the windshield," says OPP Sgt. Dave Moffat.

Emergency responders had to cut off the roof of the pickup to get the 61-year-old man out. He was airlifted to Sunnybrook hospital in Toronto with serious injuries.

The crash brought traffic to a standstill in both directions for a short period of time.  Investigators still can't say why the tire came flying off.

"We have a couple of things to determine as to and one is why and how this happened."