well in that case i would go for hd on the rear and medium on the front to keep the flex as hd all round unless you have a winch and bumper up front limit your articulation as i found out on my green one . in this combo the rear will sit a fraction higher but when you drop a trailor on it comes back in line . also if your going +20 mm you might need a drop plate for your ball ( flat plate is what i got )