RCZ

Yes, you dont need to lower the car to install spacers.

If you don't lower it, then absolutely. If you do lower it, then probably not. The more you lower it the more you have to get a camber kit.

I think you are confusing installing spacers with installing springs. You will gain a bit of negative camber when you lower the car. Negative camber is better for cornering grip, but excessive amounts of it will wear out your tires quickly.

The ratio between front and rear camber plays a big part in dictating the behavior of your car. More negative camber up front means more grip to the front tires on corners; that means that the front tires will have proportionally more grip than the rears. If you are in a corner and your front tires have more grip, then your rear tires will slide first. That is called oversteer.

If your front to rear camber ratio is the other way around; meaning that there is more negative camber in the rear, then that will cause the front to start sliding out first. When the front tires lose grip first, that's called understeer. You are trying to turn, but the front tires dont grip, that causes you to "push" or "plow". So instead of turning where you want it to and making the arc you want for the turn, it is opening up that arc and pushing the arc wider than what is optimal.

To explain camber, I always just tell people to picture it in their minds. Your traction is linked to the physical connection between the tire and the ground. The bigger the contact patch, the more grip you have. That means that if the tire is flat on the ground, aka perfectly vertical, then the contact patch is as big as possible. Vertical would look like this "||".

What happens though, is that because the car is on a suspension that needs to be soft enough to absorb bumps, when we go into a corner the tire doesnt stay straight on the ground. The suspension flexes because of the sideways load of the g-forces acting on the mass of the car. That means that the tire is no longer flat on the ground in a corner. If you start from this "||" and you take a corner, your tires will end up like this "//". In other words, due to the flex of the suspension, etc. your previously flat-on-the-ground tires are no longer flat, but one edge has lifted off. That causes your contact patch to shrink dramatically and as we know already, smaller contact patch means less grip.

So how do you get the contact patch to still be as large as possible in the middle of a corner? In other words, we want the tire to be completely vertical in the middle of the corner to maximize grip. The answer is to start from "\\" position, so that when the suspension bends and the g-forces act on the car, it will pull it from "\\" to a "||" position. You are starting from a slight angle that opposes loads of a turn; it would look like this "// \\". That guarantees that no matter which way you turn, one of your front wheels will be flat. On a left hand turn where the car leans to the right, it would look like this "// ||" that means that the right side front tire has the biggest contact patch. That tire also has the biggest amount of grip because the weight of the car shifts to that end of the car. If you remember from physics class, pressure is one of the factors that affects grip. The more pressure, the more grip you have. If you were making a right turn then the weight would shift the other way like this: "|| \\" and the same thing would occur except with the front left tire.

When you have 0 degrees of camber, that means that your tire is like this "||". When you have negative camber, the tops of your tires are closer together like this "// \\" and positive camber is the opposite "\\ //".

I am never writing all that again, wow did I get myself into that mess and then it was too late to quit. If that doesn't get one rep I'm signing off these forums forever.

I'm not sure about the bearings, but it wouldnt be too far fetched that the greater leverage caused by the wheel being further away has unwanted effects. However I think its negligible at most.

Dont go 15/15 cause of that, just get what you like. I really don't think its going to make any difference in your life. Plus if you do get understeer....you can always go a little more negative with the camber up front and that will help you correct it.