Hi C4,
With antiskid working, you can probably apply up to 3,000 psi to the brakes, (as shown on the Y hyd brake pressure gauge with parking brake set). The antiskid system will release the brake pressure, before wheel lock and tyre destruction.
Without antiskid, you are advised to limit the brake pressure to 1,000 psi - in case you lock the wheel and destroy the tyre.
Some later modified aircraft now have an automatic maximum brake pressure limiter of 1,000 psi - (even if you press the pedals harder) when antiskid is off.