If you have a pair of jeans that is feeling a bit tight since going in the dryer (or perhaps you have gotten a bit larger) you can try and loosen the tightness in the fibres of the jeans.
First, wash as normal, then dry on delicate until damp. Then, put the jeans on (yes, it can be a bit of a struggle, but worth the effort) and wear them until dry, which will take 1-3 hours depending on the room temperature. This will not only gently stretch the jeans, but also form fit them to your exact body.
Once they are stretched, always dry them on delicate instead of on the hot cotton setting, in order to prevent the jeans from shrinking again.