Hiya Alan,
Those pressures are for road use, when we are trialing we only lower the back pressures to 15 psi, the front are so low to gain grip especially when brakeing otherwise the front wheels lock up as i'm running with drilled and grooved disc's and performance pads on the front. Plus due to the exagerated camber angle (due to wheel diameter) i'm useing the whole width of the tyre tread and to ensure the tyre temperature is kept even accross the tread 10psi is enough to keep the tread flat on the road and the last reason is due to the front of the buggy being so light! hope this helps.
Christine & Lee