Assuming you have a single, rigid rear axle connecting the two wheels, you could set it up (in 3DSMax) so that the axle is skinned to a bone that is rooted at one of the wheel hubs (let’s say the left one), the tip/end joint of which is located at the hub of the opposite wheel (the right one). I guess this is what you’ve already done in Max with constraints.
You can build a similar constraint in UE, in the animation BP, by using a LookAt node to make the bone constantly update its orientation correctly as the wheels move up and down.