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Old 02-08-2012, 12:02 AM
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NWRQC NWRQC is offline
Dodge Ram Forum Senior Member
Join Date: Dec 2011
Location: W.A
Posts: 730
Gender: Male
Vehicle: 2007 RAM
Engine: 2007-2011 409ci (6.7L) Cummins Turbo Diesel 350hp 650lb/ft
Rep Power: 5
NWRQC will become famous soon enough

The wheel offset is measured from the center of the wheel to the mounting surface(the part of the wheel that bolts to the hub) of the wheel. A wheel of a -0- offset would have the mounting surface centered between the inner and outer lip of the wheel. So say you have a 10" wide wheel with a -0- offset, the mounting surface would be 5" in from the edge of the wheel. Now offset(where the word comes to use...."offset") comes into play when you move the mounting surface one way or the other from the center of the wheel. Moving the mounting surface towards the outer lip (face of the wheel) is considered a positive + offset. So if the mounting surface is moved 25mm outward you would now have a 10" wide wheel with a +25mm offset. The same goes for moving the mounting surface inward. If you move the mounting surface towards the inner lip 25mm, you now have a 10" wide wheel with a -25mm offset. So depending on how you want your wheels to look (and for clearance) you select a set of wheels with the right (higher or lower) offset.
The higher the offset the more the wheels will be sunken in, the lower the offset the further the wheels will stick out.
Take the stock 20" wheels they are 20x9 +18mm offset. You cant change the offset, but you can add spacers to lower the effective offset, but lets pretend that you can buy the wheels in any offset you want.
If you wanted your wheels to stick out or be flush with the fender you would buy a lower offset wheel such as -5mm offset.

If you buy spacers without studs built in, then yes you will want to replace your studs with longer and stronger ones. The easiest and cheaper route is to buy spacers with studs already pressed in. The only thing is I belive that smallest spacer is 15mm if you go that route. I have and am running spacers like those. I know tons of people who have run those with no problems.
2007 6.7 | EFI-Live | Draconian tuned TCM | T4 S366 | ARP | AFE | Fox | Carli
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