Well I am lifted 3.5" and running 33x12.5 and I had to trim (a lot of the) front and rear of my front cladding, (see my gallery to see the trimming in rear of front fender) so I am going to venture to say that they will be a bit big. I would stick to something closer to a 31" tire if you can find one for an 18" rim.

I'm not an expert on this by any means, but think your trying to go too big.