Wiley Coyote
NAXJA Forum User
- Location
- Anchorage, AK
I think you guys are interchanging offset and back spacing. Back spacing is measured from the mounting surface of the wheel to the inside of the inboard rim. The less back spacing you have the more the tires will stick out from the vehicle, generally 3.5” is good on an XJ. Offset is where the wheel mounts in relation to the width of the rim and is measured in positive and negative numbers. Say you have an 8” wide rim; zero offset would mean that the mounting surface is exactly in the middle of the rim. Negative offset makes the tire stick out further away from the body and positive offset makes the tire tuck in closer to the body. As soon as you start messing with different width rims it will completely mess you up. If you try to use the offset and back spacing numbers from an 8” wide rim on a 10” wide rim the tire will not be positioned in the wheel well the same. I guess that’s part of the fun and games when you start modifying vehicles. All of this would be much easier if rim manufactures would standardize how measurements are taken, but I’m not holding my breath. :laugh3: