According to the kobuki tutorials, the kobuki base controller already publishes odometry on the /odom topic. Why do you need to reinvent the wheel and compute your own odometry? (And I can't find any topic which has the raw values either.)

Thanks for the reply hopefully I've deleted the duplicate question. (though I could still see the supposedly deleted post on my account page:/) I was trying to follow rosodom tutorial, was thinking that it would be better to sub to real values rather than hardcoded ones as suggested in that tutorial