Fleet bosses fell foul of spot checks on tyre safety at an industry get-together.
More than 12% were driving cars with at least one dodgy tyre, it was found.
Checks in the car park for this year's Company Car In Action event by Kwik-Fit technicians found 128 vehicles failed out of 1,030.
Kwik-Fit fleet director Simon English said: "Fleet executives should be leading by example and ensuring that the vehicles they drive are in first class condition.
"It is not only their safety but that of other road users which they are jeopardising."
Company Car In Action is an annual product showcase for vehicle manufacturers and fleet executives held in Bedfordshire.
