Rhythm Practice
Rhythm Reading Exercises
Scroll down to the exercises
You should be able to clap the basic level & basic-intermediate
http://www.samuelstokesmusic.com/rhythm.html
Teoria: This site offers online practice for rhythmic and melodic
dictations
http://www.teoria.com/en/exercises/rd.php
Below are a few other useful sites
http://www.auralworkshop.com/rhythmbeginner.htm
https://www.sightreadingfactory.com/app - select rhythm only
http://www.fundamental-changes.com/sight-reading-rhythm-part-two/
http://www.learningtoplaytheguitar.net/nutting-out-rhythm-notation/