Is backspacing the same as offset?

[00S104.3]

When shopping for wheels is backspacing the same thing as offset. Some wheels say 4" backspacing and some say -11 offset. Do these numbers mean the same thing? Thanks for the help in advance.

[Sparky2263]

Offset can mean quite a few things. Backspacing on a wheel leaves no room for doubt.

The distance from the mounting surface to the back edge of the wheel in a vertical plane (or horizontal if the wheel is laying down ;) ).

But yes, they are used interchangeably, much to many an old-timers chagrin.

[00S104.3]

Thanks sparky. I thought they were the same because they never mention both backspacing and offset at the same time it's either one or the other but I thought I'd ask to be sure.

[turbodog]

Backspacing is the distance from the inside (back) edge of the wheel to the wheel mounting surface (bolt-up face).

Offset is the distance from the wheel mounting surface to the centerline of the wheel.

Offset = [1/2 wheel width] - [backspacing]

http://www.311s.org/Pics/offset.jpg

[00S104.3]

Backspacing is the distance from the inside (back) edge of the wheel to the wheel mounting surface (bolt-up face).

Offset is the distance from the wheel mounting surface to the centerline of the wheel.

Offset = [1/2 wheel width] - [backspacing]

http://www.311s.org/Pics/offset.jpg

Ok, that helps a lot. I was looking at 17x8" Torq-thrust II's on ebay and it said you can get 4" or 4.5" backspacing. Does anyone know offhand which one would be best? I don't care if they rub a bit at full lock turns but I don't want them to rub at all under normal driving conditions and still tuck. I am going to do some measurements but I thought I would ask you guys too. Knowledge is power. Thanks

[Sparky2263]

Excellent info there turbodog!

[20Xtreme02]

The higher the back spacing the more wheel inside the wheel well. The factory Xtreme wheels on my 2002 Blazer had a 4.5" back space. I went with 17x8 Eagle Alloys with only a 4" back spacing. The difference in back spacing wasn't enough to notice. I can't tell that the wheels stick out any further than the stock ones. A little less back spacing than stock might help ensure that there isn't any tire rub at full lock if you go with wider tires.

[00S104.3]

Thanks 20Xtreme02!