is it ok to shift into 2nd gear while going 60+mph?

Xan

There are many reasons why it's only an estimate.
Some reasons are that how the tire deforms, which is influenced by another 100 things. So I used a general rule. The gear ratio's and final drive I used might not be excact, I just got them of the inet. And so on, at the same time if your accelerating up to red line, than quickly shift, there could be some inertia that accelerates the car while you already pushed the clutch. And how many people would keep a car at red line steady state second gear to see their speed. :-)

Anyways moral is the only way to truly know is using the fun way, the excel sheet way is just an indication.