9.00-17 is the old way of measuring tyres..

it means a rim from 17 inch and a tire with a 9.00 inch tire side (from the street to the rim)
i.e. 9.00 + 9.00 + 17.00 is 35 inch

where Land Rover use a lot 7.50-16 which is equal to a 32 inch tire like a 32/11.50-16 but the 32 tire is wider you want almost the same as a 7.50-16 in metric you take a 235/85-16

where a 9.00-17 equals out a approx a 255/75-17