Quote Originally Posted by larry_arizona View Post
Technically you would only raise trailer height 1/2 of 0.7”= 0.35”
almost every boat dealer out there told us 1.5-2" if you add 18's to the trailer and we confirmed this with a few phone calls and a couple of the websites show 1.5" for 18's under boat specs.
I am assuming that you also might need to factor in axles getting clocked a little higher for the rims due to width.

be careful using tire load ratings. our boatmate trailer has a max rating of 7500lbs on the sticker. each axle is rated at 3750lbs. this is below the ratings of all 4 tires added up.