[shiroiuma]

You're overinflating your tires. A lower pressure will increase your speed and efficiency unless you're riding in a velodrome. Here's a video about this:

https://www.youtube.com/watch?v=7r8f3w89XeM

(watch out, there's a lot of extra stuff in this video about the machine they use to measure efficiency)

[deathanatos]

(Well, they should tell the manufacturers…)

The video's result for both tires they tested was peak efficiency at 5 bar. They had a really coarse sampling of a whole bar, so that works out to a pressure of 65–80 psi.

[shiroiuma]

>(Well, they should tell the manufacturers…)

The manufacturer rating is likely a max allowable pressure rating.