oh my oh my... rule # 1 - never stretch a tyre into different size rims... you'll break the bead around the tyre rim and it'll just a matter of seconds before the tyre sidewall gets rip apart... mind you that V35 is a relatively heavy car - around 1700kg - they will put more stress to tyre than a 900kg Toyota Starlet. so play it safe....
well if you know your 18" offset, PCD etc, just find a set of 19" with the similar spec in terms of width & offset. anything around 1 inch variance or around 5-10mm offset variance to the stock one might fit. rear is wider so they're easier to fit more aggressive offset at the back than front, as the front you need to find as close possible as to stock so when you turn your tyre don't rub the inner guard, and shave off the corner of your tyre, or causing dented guard.
if you don't lower your car pretty much anything would fit...
here's 19x8.5+30 & 19x9.5+25 look on my car...
V35 are huge car, and even 19" looks small on it. But going 20" or over means you get hardly any sidewall protection over potholes, and will likely be bending the rims if you're not tip-toe-ing around avoiding potholes while driving...