Strange that it would work for some games and not others, so probably not a main mame.ini setting.
Check the ini folder in the mame folder to see if there are individual rom ini files overriding the main one.
What exactly do you mean they "don't work"?
Is the wheel not detected when you try to map it in game? (TAB)
Some games might require you to calibrate it in the service menu (usually F2) first, but the wheel should still be detected when you map it.
See the MAME section of the stickied Driving Cab Info thread for other important settings if you haven't already.
MAME games with analog controls aren't like digital joystick games where you can just install MAME and play them all.
They each need set up individually (especially the wheel sensitivity) to get them to feel right.