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Originally Posted by bmwm750
Jim-
I thought about the potential weakening to the wheel center, however (and please do correct me if I am wrong), the center hub area is solid alloy, as its where the lug bolts go through, so taking off a few mm of material shouldnt have a profound effect on the overall integrity of the wheel as a unit, or am I completely off base with my thinking?
Patrick
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Hi,
Well, there are several things to consider. Tensile Strength will be the result of the Alloy used, it's thickness and temperature.
Since lightness/strength is the goal of the Wheel Manufacturer, I doubt that there is a lot of excess material. Remove some, and you can quite easily end up with an
Ultimate Tensile Strength (the point at which the metal fails) which is much closer to the forces which the Wheel can experience, even the removal of just a few mm.
Additionally, Aluminum is subject to Fatigue failure (referred to as its Endurance Limit). The design solution is to increase the thickness so that deflection is kept within the allowable range. Again, machining away material can easily compromise the design.
Then, the Machining itself must be considered. If not done properly, the process can create lots of micro-cracks, which could spread when under stress leading the Wheel failure.
The forces to consider are not those normally encountered, but rather those brief sudden high impacts such as potholes and such where the forces against the Wheel are multiplied many hundreds of times. I would be more concerned with the cumulative, not the instant effects of these impacts. This cumulative effect is a concern for non-altered wheels, more so if you start machining them.
Too much information is lacking to state unequivocally that a few mm wouldn't make a difference. They could, in fact, make
ALL the difference. The only way to be certain would be some destructive testing, which you cannot do. Again, I think it's ill-advised...
Happy Motoring!... Jim'99