The speed at which you can drive in 4-wheel drive high depends on several factors, including the vehicle you are driving, the conditions you are driving in, and the type of terrain you are traversing.

In general, 4-wheel drive high is best suited for off-road driving and situations where extra traction is needed, such as driving in deep snow, mud, or sand. When driving in 4-wheel drive high, power is distributed equally to all four wheels, which provides better traction and stability than 2-wheel drive.
Most vehicles equipped with 4-wheel drive high are capable of reaching highway speeds while in this mode. However, it is important to note that driving at high speeds in 4-wheel drive high can be dangerous, especially on paved roads or other hard surfaces.
The maximum safe speed for driving in 4-wheel drive high will vary depending on the vehicle you are driving, as well as the terrain and driving conditions. It is generally recommended that you do not exceed 55-60 mph when driving in 4-wheel drive high, as driving at higher speeds can put unnecessary strain on the vehicle’s drivetrain and cause it to overheat or become damaged.
Additionally, driving at high speeds in 4-wheel drive high can also make it more difficult to control the vehicle, as the increased traction and stability provided by the 4-wheel drive system can cause the vehicle to feel less responsive and more sluggish.
It is important to use good judgment when driving in 4-wheel drive high and to adjust your speed accordingly based on the conditions you are driving in. If you are driving in deep snow, for example, you may need to drive slower than you would on a dry, paved road in order to maintain control of the vehicle.
In conclusion, the maximum speed at which you can drive in 4-wheel drive high will vary depending on several factors, including the vehicle you are driving, the conditions you are driving in, and the type of terrain you are traversing. It is generally recommended that you do not exceed 55-60 mph when driving in 4-wheel drive high, and that you use good judgment and adjust your speed based on the conditions you are driving in. By doing so, you can help ensure your safety and the safety of others on the road.