Thanks. You're right; I noticed that after creating the post, but my problem is not that. The deformation is due to inflation pressure. The inflation pressure expands the tire made up of hyperelastic material (Moony-Rivilin, two parameters). I tried to simulate the model with three steps. I applied inflation pressure without other loads, including gravity, in the first step. The time integration option is turned off in this step. In step 2, a constant displacement is used to generate the initial velocity for 3rd step. Same as the previous step, the time integration is turned off. In 3rd step, gravity would be applied, and the time integration would be turned on. Theoretically, this approach would lead to the desired solution, but still, the problems exist, and in 1st step, the solving process encounter error due to high deformation. It was worth saying that the reinforced belt was added to the tire to improve material strength, but it didn't work.
I acknowledge that it is possible that the material may not be proper to bear the inflation pressure (215 psi=1.482e6 pa) and bring about high tire expansion. But how could they use this material to model aircraft tire touch-down in the following Paper?
Thanks for your energy and time consuming