So I've had my Focus for 3 years + and about 44k miles. A few track days- I feel i know thee car pretty well.

Until the most recent set of tires (replaced at 38k) all tires have been filled with compressed air.

The current set has nitrogen. I had these tires installed in the spring when temps were in the high 20s (Celsius). Recently temps have dropped significantly (as well as humidity). Now the car bounces like a rubber ball after hitting a bump. Its a bit unsettling and reall hurts the 'seat of pants' feel of the car.

Granted-it could be any number of other factors (suspension, driver, etc) and I have considered these, but Occam's razor points to the nitrogen.

Has anyone else experienced a similar phenomenon with nitrogen filled tires and drops in temps?