Cruise control defective – Range Rover Evoque

The cruise control of my Range Rover Evoque works up to 95 km/h, but not at higher speeds. A mechanic tried to fix the error. He found out that his measuring instrument shows a different speed on each wheel. He asserts that this is not on the measuring instrument. Here is some information: Before the error occurred on the cruiser, the ball bearings on the rear wheels were replaced. If the juggling bearings can be a source of error: How can If the ball bearings have nothing to do with the cruise control, what can be the source of the error? Thank you in advance for all the answers