V1 is the critical takeoff speed for an aircraft at which the pilot must make a decision.
The aircraft can still safely stop if the takeoff is aborted prior to V1. The abort could be due to an engine failure, bird strike, blown tire, etc.
After the aircraft reaches V1, it must takeoff to avoid crashing at the end of the runway. But the pilot can then fly the aircraft around for a landing.
V1 depends on the runway length, wind, and on the aircraft’s weight, thrust, lift, braking capability, etc.
Vr is the rotate speed. It is not always the same as V1. At this speed rotation is begun as the pilot pitches the plane upward.
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Nevertheless, aborts do occur after the aircraft reaches V1.
Here is a report by the The NLR Air Transport Safety Institute which states that tire/wheel vibration is a cause or factor in some of the cases.
REJECTING A TAKEOFF AFTER V1…WHY DOES IT (STILL) HAPPEN?
The NLR Air Transport Safety Institute (NLR-ATSI) is a research and consultancy organization embedded in the National Aerospace Laboratory of the Netherlands (NLR).
– Tom Irvine
Vibrationdata 