Heavy vehicles with high centres of gravity are prone to rollover accidents. A combination of tilt testing of a range of articulated tankers, together with a computer model of the rollover process, has been used to determine means of improving stability. Parameters including lateral load transfer at each axle group, deflections of the sprung and unsprung parts of the suspensions and movement at the fifth wheel coupling will be presented. The effects of suspensions, couplings and tyres on the rollover limit will be discussed. It is concluded that centre-of-gravity height, track width and suspension characteristics are the main factors influencing stability. Means of implementing the results are discussed, including a Users' Guide to suspension matching and vehicle design improvements. Further research to be carried out involving full-scale dynamic testing with outriggers fitted will be discussed.