sentences:  Rule 159 Para 9
  No part of the chair may protrude behind the vertical plane of the back edge of the rear tyres.Rule 159 Para 10
  It will be the responsibility of the competitor to ensure the wheelchair conforms to all the above rules, and no event shall be delayed whilst a competitor makes adjustments to the athletes chair.Rule 159 Para 11
  Chairs will be measured in the Marshalling Area, and may not leave that area before the start of the event.