This issue is based on how the model(a wheel) is built up, thus, how many 3D-points there is around the wheel. A wheel with a great number of 3D-points will fall into the ground more easier than a wheel with a small number of 3D-points. So the problem here is high friction between the wheel and the surface the wheel are traveling on. If the surface is flat, like gm_flatgrass, it will strengthen the friction. And if the surface is hilly/bumpy, it will bring down the friction. But there are several other factors, like SPEED and as said, weight-difference, size etc. that affect the friction.
Below you see two wheels; the first with a high 3D-point value and the other one with a less 3D-point value. The second wheel is twice as large as the first one displayed(don't let your eyes foul you, the second wheel is bigger, in-game).
Here you barely see the angular shape of the wheel(the 3D-points), witch means that it will achieve a high friction even when traveling at low speeds, making it fall through the ground.
This wheel on the other hand, you can really see the angular shape. Also, as said, this wheel is much bigger, so it will require a tremendous speeds to get through the ground. But the ride will of course be a lot more bumpier than with a less angular wheel.
So.. Just pick the wheels with a more angular shape, and you will prevent failure!