Arch rolling is only really needed when you fit very wide tyres, therefore I suggest you check the following post for some known & tested wheel dimension combinations, that do NOT require arch rolling...
See [url="http://www.lexusownersclub.co.uk/forum/index.php?act=ST&f=30&t=637"]HERE[/url]
You're best bet is to stick with what's known, rather than try to reinvent the wheel. (no pun intended..

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