252 Self-help, Vehicle careChanging wheelsThere may be a tyre repair kit instead of aspare wheel – see page 256.To ensure y our safety , ma ke the followingpreparations and observ e the followinginform ation w hen changing wheels:z Park the vehicle on a level, firm and non-skid surface.z Switch on hazard wa rning lights, applyhand brake, automatic transmission 3 -selector lev er in P, manual transmissionor Easytronic 3 - engage 1st or reversegear.z Correctly set up the w arning triangle 3.Warning triangle, see page 247.z Remove spare wheel from luggagecom partment, see previous page 249.z Before raising the v ehicle, set the frontwheels to the straight-ahead position.z On the Astra TwinTop, the roof m ust beclosed before the v ehicle is raised .z Never change m ore than one w heel atonce.z Block the wheel diagonally op posite thewheel to be changed by placing wedgeblocks or equiv alent in front a nd behindthe wheel.z Use the jack 3 only to change wheels.z If the ground on which the vehicle isstanding is soft, a solid board (max. 1 cmthick) should be p laced under the ja ck 3.Using a thicker b oard c ould dam age thejack 3 and the vehicle.z No people or a nima ls m ay be in thevehicle when it is jack ed up.z Never cra wl und er a ja cked-up vehicle.z Do not start or run the engine while thevehicle is on the jack.z Before inserting the wheel bolts w henchang ing wheels, lig htly grease the coneof each bolt. For this reason, carry someconv entiona l grease.