The increased speed limit for cars will be 140kph, 100kph for buses and 80kph for trucks, the director of Public Relations and Security, Col. Sami bin Muhammad Al-Shuwairikh told Saudi Press Agency (SPA).
Updated road signs will be installed where the new speed limits are in place and drivers have been warned to not exceed them.
The roads on which speed limits have been amended include the Riyadh to Al-Taif road, the Riyadh to Al-Qassim road, and the highway to Makkah.
Al-Shuwairikh cautioned motorists not to exceed speed limits and to strictly abide by instructions on signboards.
The Special Forces for Road Security said the new increased speed limit does not mean that motorists should drive at the maximum allowed limit.