It seems many people have opinions about whether a man should wear jeans inside boots or not. The general day-to-day opinion is that guys wear jeans over standard height cowboy boots.
Some people make snide remarks about the character of guys who wear jeans inside boots. However, if you have nice boots and want to show them off, then by all means, do so! But for ordinary day-to-day wear of standard cowboy boots, jeans over boots is the way to go with one exception: Buckaroo boots.
Tall Buckaroo boots are made to be worn by cowboys when working on horses on a farm or ranch. The boots are designed to be shown. In this case, pull your socks up over the ends of your jeans, then pull on your boots so you have a nice, smooth appearance of the jeans inside your boots.
Stop obsessing about what other people may say or think about you wearing cowboy boots with jeans tucked into them. If you're worried that someone may say something, then make the choice not to wear jeans inside your boots. But it is YOUR choice – not someone else's.
If you have nice boots that you want to show, tuck your jeans into them. If you don't want to do that, then don't. It's your choice.
For motorcycle boots: the general custom (in the United States) is that one wears jeans over boots that are 12“ or shorter. He wears jeans, leathers, or breeches inside boots that are 14” or taller.