hi,
ive tucked 18x8s with 5" backspacing. used Nissan Titan 18"s with the 25mm offset (4" would be 0 offset, add 25mm offset (almost 1" more) gets you 5" bs) they BARELY tuck on the fronts, but the rears tuck nicely due to the rear track being narrowoer by 1/2" each side.