Negative Camber Doesn't Seem Right

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/6 Matt

/6 Matt

30 Degrees Crooked
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Ok so I've been quietly reading all around lately and I keep seeing the same standard skosh chart being posted. Now everything seems right to me except for the Camber. For all street settings the chart calls for anywhere between -.25° and -1° but I have to wonder how does that not wear the inside edges of your tires at accelerated rates? I was always taught in highschool (2012) that you need positive Camber so that when the passengers weight is added to the vehicle and the suspension settles you get a net 0° Camber. What am I missing here?

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In theory, if a vehicle was only driven in straight line, on a flat road, zero camber would produce the most even tire wear.

In reality, much of the wear occurs under loaded conditions (hard turns) and the combination of camber and caster help keep the wheel more upright as the body rolls and the weight shifts.
The alignment settings settings recommended by the factory were based on a couple things that have changed. One was high crowned roads were the norm (and unpaved roads still pretty common). The other was bias and cross ply passenger tires, did not require or want a lot of negative camber, and the rubber compounds as a whole were not as high grip as what's become available since the 70s and 80s.

For competition tires, the manufactures publish the recommended alignment settings. Usually this is just camber, but sometimes camber and caster. Final decisions are then made on the track, preferably with a tyre pyrometer. The pyrometer is used to measure temperatures across the treads (the goal being uniformity). For passenger and truck tires, I suspect a manufacturer's rep can provide the recommended camber range for any of their products.
 
Positive camber is for bias ply's and shouldn't be run with radials, especially modern radials.

Mattax is right on. What you want is the most even tread pattern you can get, as much of the time as possible. But that changes with how the tires are loaded, so you're trying to match your alignment up with the type of driving you do, the roads you drive the most, and the specs of the tires you run.

On my cars I've run as much as -1* of camber without seeing any ill effects on the tread wear. Like everything though that depends on how you're using the car. A car used as exclusively as a commuter with extensive freeway use would show camber wear with less negative camber than a car that's used in more mixed driving. And a car used primarily as a canyon carver or autoX car could run much more negative camber without showing any camber wear effects because of the amount of cornering being done. You could actually see wear from not running enough negative camber if the car is always cornering, just like you would see it from having too much if the car is always freeway driven.
 
this just looks wrong in so many ways. haha... never heard of anyone running positive camber on purpose (besides maybe trucks?) but I guess its probably out there.

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that's the setup i use for driving in storm drains

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Alignments should optimally set with a full gas tank, driver in car and typical load carried. Remember that the alignment that you are setting is " static ". That means the car is not moving down the road. In reality the car is actually " floating " down the road. That means that the suspension is in a constant state of compression and rebound cycles, usually about an Inch + or - on a smooth road. More on cornering. This is why you want the alignment set to the " preferred specs " for whatever your type of driving dictates. Hi-way driving, middle of the allowed spec. Cornering, more negative.
 
/6 Matt said:
the passengers weight is added to the vehicle and the suspension settles you get a net 0° Camber. What am I missing here?

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You are missing that "high school was wrong" See post 6. In theory, a well designed suspension system should NOT change much when load is added. Vee Dubs aside...........

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BMW specifies full tank and preloads suspension to simulate passengers before alignment is done. Unless you don't go to BMW to have it done. Normal alignment shops do not have proper tools to do most European cars correctly. More than just a toe set.
 
MoparLeo said:
BMW specifies full tank and preloads suspension to simulate passengers before alignment is done. Unless you don't go to BMW to have it done. Normal alignment shops do not have proper tools to do most European cars correctly. More than just a toe set.
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I remember a few years ago the BMW dealer in Berkeley would put a few weights on the front seats to simulate occupants weights. I get that and I know the mainstream tire shops don’t do that. But, F’ing A, man, they would charge like $250 for a friggin wheel alignment. Seriously!?!! You charge 2 1/2 to 3 times the price because you guys have sand bags in your shop? What a rip!!!
 
It all depends on what you're driving and what you're doing. Positive camber has its place just like negative.
 
Any negative camber wear issue is generally covered by adding a small amount of extra toe IN...Theres no denying that increasing caster and some negative camber will make the car handle better....I have aligned a few thousand cars I guess...Ive also loaded the car to fix problems etc ( 400lb woman etc). A lot of times the factory specs are not the best to achieve decent steering, especially older cars ... tyre technology has changed a lot too
 
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