For the pedals in MAME you have to set them two times each, at least i have had to with the game. For example hit enter on pedal1 then press the gas and it will show that pedal set, then hit enter again and press gas again, it will now add a + after the name, (this will vary by game, Ridge Racer for example needs them to be on - not + so you have to set them three times in that case). You dont really need to do anything in ghub other than adjust the wheel range down from 900 to something more comfortable, somewhere between Koroths suggestion of 270 and 360 would be about right in my opinion. I just setup a ghub profile for MAME and changed that there, so it auto locks to 270 when i load MAME now.
Id suggest going to your mame/cfg folder and deleting the one for this game and starting it from fresh, it should just be as simple as selecting paddle and turning the wheel, then pedal 1 and 2, which you do twice each to get the + after the input name.