Umphetho wevili lesithuthi licandelo lentsimbi ecylindrical exhasa i-contour yangaphakathi yetayara kwaye igxile kwishaft. Kukho iindidi ngeendidi zamavili ngokuxhomekeke kububanzi bazo, ububanzi, indlela yokubumba, kunye nezinto.
Xa i-diameter yangaphandle yetayara ihlala ingatshintshi, kuyimfuneko ukutshintsha i-rim yevili kunye nesondo elinomlinganiselo ophezulu. Oku kunciphisa i-lateral sway yesithuthi, okwenza kube nokuzinza ngakumbi ukuqhuba kunye nokubonelela ngemvakalelo elula xa i-kona. Kodwa indleko kukuba ukusebenza kokufunxa kuyancipha kakhulu, kwaye i-bump encinci iya kuhanjiswa ngokucacileyo kwisithuthi, ukunciphisa kakhulu induduzo. Ukongezelela, amathayi athambileyo kunye namancinci anokuchasana buthathaka kumandla angaphandle, ngakumbi xa ebethelwa zizinto ezibukhali, zonakaliswa lula.