PIAA 2100 Series - Manual (Page 6)

DRIVING LIGHT
AIMING
Typically, driving lights are mounted above the front bumper about 14-30 inches
from the ground to provide extra high beam illumination. Driving lights can be
mounted below the bumper, although they will not be as effective because the
light will hit the ground sooner and reduce the range of the light.
Visual aim is made with the center of the beam hot spot 1.5 inches below the
lamp center at 25 feet with the lamp facing straight forward. (see below.)
Do not use driving lights into oncoming traffic.
Driving lights should never be the only foreword light source.
Driving lights should only be used with the headlamp high beams.
Only use fog lights if they are aimed properly.
Fog lights should never be the only foreword light source.
Fog lights should be used with headlamp low beams.
FOG LIGHT
AIMING
There are two important issues to address when installing fog lights, the first is
to minimize the amount of return glare into the drivers eyes, and the other is to
minimize glare into oncoming eyes. Both of those issues must be accomplished
while putting as much light as possible on the road.
These fog/foul weather light aiming instructions are suggestions taken from
common practice and the S.A.E. standard J583. Some modifications to these
instructions may be necessary to minimize glare.
Visual aim is made with the top of the beam 4 inches below the lamp center at
25 feet with the lamp facing straight forward. (See below.)
5.