Team worried about robot tipping while crossing rail.

[Nikkocharger]

Hello everyone

My team is finished building the prototype chassis but we are worried about the robot tipping while crossing the rail. Since our middle tire is about 3/4 of an inch lower than the front and rear wheel it raises the whole chassis up pretty high. One idea was to make the middle wheels smaller and put omni wheels on either the front or back wheels to aid with turning. How ever we can't put omni's on the front because the may break from being rammed into the railing. We also can't put them in the rear because the robot would lose traction driving onto the ramp.
Also with all of that weight coming down at the same I wondered would this cause excessive weight and stress on the rims causing them to break.