Minimum tubed tyre pressures for offroad/trials?

[stinkwheel]

Got some mates coming to do a long distance trial with me next year. Total novices.

I run stupidly low tyre pressures in my trials bike and still struggle for grip. Like 6psi for the slithery mud you encounter on this trial. I've got heavy duty tubes, oko anti-puncture goop and rim locks.

Couple of the guys will have bikes running tubeless rims with roadgoing enduro-style tyres (there is a special class-x which allows non trials compliant tyres for people wanting to dip their toe in the sport). I was wondering if there's a working minimum before you risk them coming off the rim? It'll be mostly low speed stuff. Max speed limit on offroad sections is 15mph. Tyres can be pumped up again for road sections.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Copycat73]

no rim locks ... wouldn`t drop below 25 .. front or rear .. but then again i dont ride in the slop .. frankly they are dammed either way ..
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caveat emptor

[tatters]

Min 20 PSI for tubed tires with no rim locks

Min 15 PSI for tubeless tires. The bead of a tubeless tire will hold on the rim a lot better than a tube type tire at lower pressures. I would be more worried about bending/denting a rim from rocks at lower pressures than a tire coming off the rim, and a tubeless tire rotating on the rim is not going to rip a tube valve off as you would get with a tubed tire.

Have ran both a KTM 1190 and a R100GSPD both big heavy bikes at 15 PSI offroad in sand/mud with no issues.
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