Stock Crossfire and Mercedes use a cone type ball seat,, aftermarket use a taper seat.
as for length the front (you can use longer bolts) and because of the offset of the stock rims,
you have 30 offset on the front, where as on the rear you have 20 offset ,that is why the stock
lug bolts are the same front and rear. I posted all this info 5 or 6 years ago,, but here it is again.

Bolt taper and ball

Bolt taper and ball



crossfire

crossfire tire specs

19" tire chart Tire size max height 26.9 stock 26.0 285/35-19= 26.9 & 11.2 wide see tire chart

18"tire chart

20" tire chart

ball and taper bolt. hope u can see this

another 20" tire chart