- The type of vehicle being driven
- The posted speed limit
- The weather conditions
- The traffic conditions
In general, commercial trucks are limited to a maximum speed of 65 mph on interstates and 55 mph on other roads. However, some states may have lower speed limits for commercial trucks, and drivers may also be required to slow down in certain conditions, such as when driving in poor weather or in congested traffic.
As a result, the average speed at which a commercial truck driver can legally drive in a day will typically be between 55 and 65 mph.