Rim Size Variance

[lkv0315]

I'm shopping for new rims/wheels, depending on what you call them and am trying to find an acceptable amount of deviation on offset, and width, since 18in diameter are a factory option anyway that should be fine. Some wheels I like are like 18x8 +35 offset which is 0.5in thickness difference from both the 8.5 and 7.5. Is this acceptable or will this damage the vehicle? and what is a reasonable offset variance, since I've read it doesn't have to be exact, but it should be close.
(Edit) Is it possible to convert do a different lug size? I feel like this would go back to doing a lug bolt to stud conversion.