The Lorenz equations show this. Length contracts as speed increases. Time expands as speed increases. Scientists have been graphing time, as if it were a length, for hundreds of years. To the left is a typical graph, showing two things in motion, one to the left and one to the right.
Time never behaves exactly like a spatial dimension.
You cannot go backward in time. And you normally cannot go forward at different rates. But, there are surprising parallels. For some purposes, it is handy to call time a fourth dimensions. For other purposes, it is not.