what does positive offset mean versus negative offset in regards to wheels? - BMW M5 Forum and M6 Forums

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Old 9th November 2003, 05:19   #1
Magna
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what does positive offset mean versus negative offset in regards to wheels?

Below is the link and info of offset from tirerack. is their diagram an example of negative offset or positive?

my wheel is 47mm offset and if i had a 40mm offset wheel, what does that mean? more strain on my car? better handling?

any info would be great!


http://www.tirerack.com/wheels/tech/offset.htm

The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types.

Zero Offset
The hub mounting surface is even with the centerline of the wheel.

Positive
The hub mounting surface is toward the front or wheel side of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.

Negative
The hub mounting surface is toward the back or brake side of the wheels centerline. "Deep dish" wheels are typically a negative offset.

If the offset of the wheel is not correct for the car, the handling can be adversely affected. When the width of the wheel changes, the offset also changes numerically. If the offset were to stay the same while you added width, the additional width would be split evenly between the inside and outside. For most cars, this won't work correctly. We have test fitted thousands of different vehicles for proper fitment. Our extensive database allows our sales staff to offer you the perfect fit for your vehicle.
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Old 9th November 2003, 13:27   #2
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The Tire Rack diagram shows positive offset.

Offset should be kept near stock. Each car's suspension geometry is designed to work best with a particular offset. Changing the offset will adversely impact suspension geometry, degrade handling and place unintended loads on suspension parts and wheel bearings.

Generally speaking, wheel spacers are a bad idea & should be avoided. A +35mm offset wheel with a 10mm spacer is geometrically identical to a +25mm offset wheel. The problem is that spacers cause wheel bolts to loosen and a wheel wobble from poor fitment, indexing or wheel centering. A wheel can come off. Factory hubs are not designed for spacers & wheel bolts see unintended loads.
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Old 10th November 2003, 00:17   #3
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Hi Thanks for the info: Going from +47mm to +40mm offset, is that a big difference or it is considered close to factory specs.

I take it that BMWs wheels all have positive offsets?


Any advantage/disadvantage to having positive offset wheels versus negative offset wheels?
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Old 28th June 2009, 10:02   #4
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Hey there, im quite comfused about this offset issue as well, not knowing if its a matter of providing clearence or handelling. My car felt perfect with the stock 19'' wheels with 5 mm H&R spacers around all four corners untill i installed my new ac schnitzer type v 20''rims. The rims are offerd with a spacer kit of 20mm for the back and 7 mm for the front to meet the oem offsets for front and back, so i installed a 20mm spacer at the back but I went for a 10mm spacer in the front insted of 7mm for the sake of looks thinking that it wont matter if they stick out 3mm more in the front. So what i notice now compared to my 19's setup is that the steering wheel feels much lighter than before, ie. the steering wheel requires less effort to turn it as it was much stiffer to steer left and tight. So could that be from the extra 3mm offset i added on the front wheels? isnt it better to stick out the wheels to minimize understeer?

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Old 28th June 2009, 15:56   #5
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Quote:
Originally Posted by Lscman View Post
The Tire Rack diagram shows positive offset.

Offset should be kept near stock. Each car's suspension geometry is designed to work best with a particular offset. Changing the offset will adversely impact suspension geometry, degrade handling and place unintended loads on suspension parts and wheel bearings.

Generally speaking, wheel spacers are a bad idea & should be avoided. A +35mm offset wheel with a 10mm spacer is geometrically identical to a +25mm offset wheel. The problem is that spacers cause wheel bolts to loosen and a wheel wobble from poor fitment, indexing or wheel centering. A wheel can come off. Factory hubs are not designed for spacers & wheel bolts see unintended loads.
Well said and I totally agree about spacers. Do not believe in them. If the wheels are properly designed for your car there is no need for spacers.

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Old 28th June 2009, 17:06   #6
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