when the rubber hits the road
when the rubber hits the road
The point at which someone's or something's efforts, resolve, or viability are put to the test; the point at which things become truly or meaningfully challenging. The government has pledged support for our efforts. Now the question is whether they'll honor that commitment when the rubber hits the road. Her plan sounds good on paper, but seeing how it is implemented on a practical level will be when the rubber hits the road.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.