6.25" Backspacing would be best based on my experience for the 10.5" wheel.
The 6.9" would place the tire in the wheel well a little more than I would like. In addition anything more than 6.5" backspacing on a 17" wheel will start hitting the nut on the lower A arm holding the upright. However this may not be a problem with an 18" wheel
Your answer is maybe! with a 1/2" to 3/4" spacer yes just need longer wheeel studs
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