What PSI for downhill bike tires used for road biking? I bought a downhill bike from a friend awhile ago when I was considering trying out downhill biking. Currently, I want to use it to do some road biking. The tires read 29 PSI 2 bar, Max of 80 PSI. I pumped them to 29 PSI, and that biking session was pretty tiring. I pumped it up to 40-ish PSI and I can coast, and pedal much better. My friend at work suggests I pump it to the max of 80 PSI, but just want to be sure this is a good idea before I try it.

I'm pretty new to the technical side of biking/bikes.

Cheers.

Update: I forgot to mention that I read this post but it doesn't really mention road biking.
You will have lower rolling resistance at a higher pressure   

A lower pressure puts more tire in contact with the ground for traction.
In the dirt this can be important.  

But you are running on the street.
Yes traction on the street is also important.
But your downhill tires are not going to have good traction on the street.    

Downhill bike and downhill tires on the street you are looking for low rolling resistance.
So pump them up to the max and no hair pin turns at 20 mph.  

If you are going to ride on the street you could mount some street type tires.
And they have tires for a mix of dirt and street.  

This is probably a duplicate some where.
I did not search.