It's called an assumption and is used to isolate the problem and aid diagnosis.
As someone with a Honda Blackbird and history of going fast in fast cars, we can deduce that there is a reasonable amount of past experience, understanding of road conditions, and the affect they have on car stability.
But sure, let's just pretend the OP was driving on a sloped, icy road, with bald tyres, in a gale, with half a tonne of lead in the passenger seat and treating the throttle like a kick drum.
well you must know how much a 350z can tram line in the ruts of a lorry now do that at double the speed limit dropping in and out of them could well give the feeling of uncertainty with all your pissing contest experience