Q: What’s up with the cars that have their tires tilted in on top and sticking out on the bottom? Is that supposed to help with performance somehow?
A: You know that expression, “If a little is good, then more is better?” This is not one of those situations. The folks who do vehicle alignments would call what you’ve described excessive negative camber. Camber, along with caster and toe, make up the three adjustments to your vehicle’s alignment. Each of them contributes to your car’s safety (or takes away from it if adjusted wrong.) Let’s take a look at what they all do.
Toe: Think of your tires like your feet. If your toes are closer together than your heels, you have toe-in. From there, toe-out is obvious. Adjusting toe influences over- or under-steer. Too much toe in either direction can cause instability and excessive tire wear.
Caster: You know how on a bicycle the front fork doesn’t go straight down from the handlebars, but instead angles forward as it goes down? That’s (positive) caster. Positive caster increases straight line tracking and improve high speed stability by making the wheels want to return to a straight ahead position.
Camber: This is the vertical tilt of the wheel. When the top of the wheel tilts away from the car it gives you positive camber; when it tilts inward it’s negative camber. Camber is measured in degrees from vertical. Modern road cars are set up with neutral or slightly negative camber, and by slightly I mean generally one degree or less. Old race cars (back in the 30s) had positive camber, but advances in vehicle design made that obsolete. If you only drove in a straight line, you’d never need camber. It’s an adjustment that’s meant to find a compromise between driving straight ahead and what physics does to your car in a corner.
In order to maximize traction and braking you ideally want the full width of your tire tread on the pavement at all times. If you have your camber set to zero and you’re driving straight that’s what you’ll get. But in a corner the forces exerted on a car as it changes direction tend to tip the wheels a bit, and since extra traction is especially important while cornering, vehicle engineers add a little negative camber to compensate. For those of you doing the geometry in your head, yes, in a corner the outside tire benefits from negative camber while the inside tire actually fares worse. But that’s okay because the outside tires bear most of the load in a corner.
Unless you’re a race car driver, any more than a degree or so of camber is going to make the drivability of your vehicle worse. Excessive camber can make a car feel jittery. If one tire loses some of its grip it can cause the car to lurch in that direction. It increases tramlining – the tendency of a vehicle to follow the ruts of the road. It decreases straight line traction and braking. It causes excessive tire wear. I could go on, but you get the point; there is no upside to excessive camber. Except.
If there is no upside, then why do we see it on so many cars? I’m not talking about a little extra camber. I’m talking about the cars with wheels tipped in so far that it looks like King Kong is riding in the back seat. Objectively, excessive camber decreases your car’s driving performance, but subjectively, well, there’s no accounting for taste. Excessive camber often gets paired up with lowering a vehicle. Tipping the tops of the wheels in allows a car to get even lower as the tires tuck inside the fenders.
Some people like the look of lowered cars with extreme camber. I’m not debating the aesthetics. We all have our own quirky favorites. For example, the Pontiac Aztek has been panned as possibly the ugliest car in modern vehicle history, but there’s also a thriving fan club for it (and I’m pretty sure most of the members didn’t join out of irony.) But personal expression has its limits; let’s draw the line at the point where vehicle modifications decrease the safety of a car. Messing with vehicle alignment, especially in extreme ways, destabilizes a car, increasing the risk of a crash. My advice to anyone considering extreme lowering and camber: Unless you plan to trailer it to car shows, don’t spend money to make your car perform worse.