This is a time-consuming process, however, it is possible to do so. Here is the process of changing a flat-tyre without a jack: 1. First, make sure that you are not parked on solid ground like concrete. You need to park the car on the ground where you can dig a hole. 2. Next, place some solid material like wooden board or bricks under the chassis to support the car when changing the tyre. 3. Remove the wheel cover and loosen the lug nuts halfway.4. Dig a small hole under the flat tyre and proceed to remove the lug nuts.5. Replace the flat-tyre and refill the hole you dug.6. Tighten the lug nuts after you ensure that the hole is fully covered.7. Replace the wheel cover and you are done.