These are legal for road use as driving lights “if” wired up with the vehicles high beams.
Spot lights come as two different types "spot light" and "spread light". These two combined will give the best result for additional lights and are normally sold as a pair.
Spot light is used for shining a lance or ray of light helping to increase visual distance at night.
Spread light is used for flooding the roads edges for a much shorter distance than the lance beam.
With both combined distance and a broad short distance will be revealed to the driver at the same time.
Driving Lights on a Toyota Hilux.
Spot lights work best at the same height as the vehicles factory lights / head lights, so these are commonly added to a bull bar or nudge bar, providing the 4 wheel drive is fitted with one.
There are many different sizes and strengths of spot lights, most use halogen which draws a lot of amps from the battery, currently HID lights or High-intensity discharge lights provide more light from less power but they’re very expensive compared to regular halogen lights / spot lights.
LED lights or light-emitting diode are becoming more commonly used as well and these draw even less amps than HID however as driving lights or spot lights they are not as bright as HID's but as technology improves it’s only a matter of time before LED will be better.
Other than those options there is size and output of the light to consider,
this really comes down to the individual’s needs and funds available.
Also to keep in mind the larger the spot light the more current it will pull from the battery and alternator.
Off Road Driving Lights.
any lights are above the height of the head lights they can only
legally be used off road. Having lights attached to the roof rack or roof in
general is actually illegal to have unless they are switched on from outside
When driving off road the traveling speeds are usually low 5-60kmph. With those kind of speeds a driver will get way more benefit from flood lights than spot lights. This will help in avoiding branches poking across the tracks, animals hidden in the bushes that may suddenly cross the track and anything else that might be in the way or close to the track.
Roof lights can also be great for setting up camp at night as the light is nice and high. Roof lights will also assist in recovering other vehicles at night time.
If owning a 4 wheel drive one would more than likely end up reversing in poorly lit areas from time to time. Stock reverse lights are rarely good at lighting up the area behind the 4 wheel drive. This is because the reverse lights on all vehicles (a part from a very few) are designed to only signal other motorists that the vehicle is reversing.
The best type of light to use is an LED with a spread beam (flood light) to
cover a wide area behind the vehicle.
If towing a trailer having one on both the trailer and 4 wheel drive would be very handy.
This is great when off roading as well. Being able to see what's behind can save damage to the vehicle, track and possible help prevent reversing into a ditch or over an edge.
If 4 wheel driving with a camper trailer it would be considered a must to have
at least one good flood light on either the vehicle or trailer.