Originally Posted by kwisn
"I made this video clip a couple years ago when there was a lot of mis-information about how a trials tire worked and what PSI to use. This might be useful to you at some point.
The key point that people keep missing is that this is a RADIAL PLY tire and the real work is done by the tire body. The knobs just add some edges for a little more bite, but it’s the flex of the tire that matches the shape of the ground that does most of the work. The spaces between the knobs are calculated to give just enough room for the knobs to close as the tire conforms to objects. You can see how this works in the video. When you spin this tire, the tread can no longer match the shape of the ground, but do a quick dip in the power and the tire will “hook up” again.
Pumping the tire up above 6 PSI stiffens the body and makes the tire more “round” with a much smaller foot print and then overworks the knobs. At 3 to 6 PSI, the knobs and tire body work together. Guys that pump this tire up to 10 PSI or more and then do burn-outs are missing the point completely.
I have some more training videos on this site that we have been using to help new people to the sport get a good start with some of the most important fundamentals. I’m not sure if this link will show my other clips or not. If not, you can let me know and I can direct you to them if you are interested.
Curt Long "
Copied from an email sent to me from the trails/recreation manager for the Entiat Ranger District out of the Okonagan and Wenatchee National Forest. Great guy, Randy. Thanks!
I run a rear trials tire now and then on my woods bike...currently a 320 lb KTM 690 and I run about 12 psi in the tire and it still works very well on the bigger bike. The only drawback is that the bike goes much faster than a trials bike and sees pavement now and then...so tread block loss becomes an issue. Still cool to see the video.