Each auto insurance policy is different and defined by each state law and/or company filing guidelines. For example in a Florida auto police generally defines "Collision" as the impact of your insured car with another object or upset of your insured car.

Collision coverage is intended to cover things that your vehicle strikes while Comprehensive coverage is intended to cover things that strike your vehicle. Comprehensive is supposed to cover un-excluded loss other than collision or overturn.

It can be difficult to determine which occurrences are covered by collision and which is covered by "other than collision" (comprehensive) when discussing objects. If you drive straight off the roadway into a ditch your loss is a collision even though the ditch is a stationary object.

Occurrences like theft, vandalism, falling objects, hail, water, wind and striking animals fall under comprehensive BECAUSE they do not fall under collision coverages.

It would appear to us that a wheel coming from another vehicle would be covered under your collision coverage, however to find out under which portion of your physical damage policy your insurance carrier believes this claim should be filed under discuss it with your agent and claims adjuster. Your insurance policy should pay for these damages less the deductible that applies to the collision or comprehensive portion of your policy, whichever your insurance company determines this claim should be filed under.

If the driver stopped that had their wheel fly off their vehicle and you received their insurance information you may want to see about making a claim under their property damage liability policy. You can see if their insurer believes that the other driver should be liable for the damages resulting from this incident.