Hi,
As matacaibo correctly says the clearance problem you will have is between the front strut spring-cup and the tyre - especially if you're thinking of some some knobbly treaded jobs.
I'm running 235/55 17s (one size wider than the original 225s) and there is about 5 or 6 mm clearance which you need to allow for the tyre flexing when cornering at speed. Check how much space you have at the moment.
Both the sizes you've mentioned are much, much bigger in diameter than mine, about 2" I estimate, and I don't think you have any chance of fitting them without spacers.
A lift kit will do nothing to increase the tyre/strut clearance.
A much cheaper solution is to stay with your 17" rims and fit an AT tyre.
You haven't said why you want to change.
I know there are lots more choices in 16" sizes, but there are a few very good 17" ones too.
I'm off road every single day in the winter, and I have not stuck yet, but I've often had to help some folks with super-aggressive looking tyres who lacked the off-road driving experience to cope with muddy/sticky conditions.
Please note I said lacking experience not ability.
On the other hand there are folks around who think that plenty welly, and chunky tyres will go anywhere. Brute force and ignorance gets them stuck.
Think carefully before making any big changes.
Cheers, S.
