The profile of the new tyre will need to be around 40 to fit in the arches without rubbing, if I recall correctly there is quite a bit of suspension travel on these, and adding 100mm to the rolling circumference of the wheel is quite likely to cause problems. However, on stiffer springs you may well get away with it..
Most if not all alloy wheels will have the specs on the back of them like the ET which is the offset and the smaller the number the further out they will go (widen the track) . they will also have the PCD and that is the number of studs and their diameter for example 5 X 114.3 or 4 x 100 etc plus the width and diameter. for example say 18 x 7.5 JJ
You can check the fitment on the "will they fit" site as that will enable you to discover exactly how they compare against your stock wheels.