Early mountain bikers often came from the road tradition where high pressure tyres meant lower rolling resistance and more speed. The same approach applied to mountain bikes would cause the wheels to skip and jump on even small bumps. This could cause violent vibration of the handlebars where you had to hold on with all your might and didn't even dare let go of the grips in order to apply the brakes. A real white knuckle ride!
When we tried lower tyre pressures we ran into all kind of problems; the skinwall tyre' side walls tore and streched, valves ripped out as the tyres slipped on the rimms, not to mention the pinch punctures.
The tyres back then were too often fat but weak copies of skinwall road tyres. Modern tyres are far tougher and grip the rims well at low pressures. Back in the 80's the only tyres that could be run low pressure were the 650b x 2" Nokia Hakkapellita snow tyres from Finland. They were a revelation, 15lbs/square inch, no pinch punctures, and with the right rim tape, no valves ripping out. They could handle corrugated bumps up to about 40mm before the vibration became uncontrollable and you were forced to slow down or lose control. Each tyre did however weigh 3lbs.
Respect is due! ... But what a good laugh.. which is fine 'cause we've all tasted mother nature's obstacle's and thought that 90's colour clash clothing was cool.. ... stop it now, it hurts!