18" rim and tire question

[DC1]

Hi, a friend of mine has some tires he wants to sell me, he has two sets both 18" I have a 1999 Series 2 with 18" rims. I believe my tires are 255/55/18. The tires he has are 18" he told me one set is close in profile but wider, the other set is the same width but taller. I cant reach him or get the tire sizes can anyone let me know if you think either set will work? Its a bit of a drive for me to go there I hate to do it and have them not fit. What is more important the width or the height? Or both? Thank you. My land rover is stock with performancer package etc. i think my rims are hurricanes.