A car that pulls is telling you something specific, and the specifics are how you avoid paying for the wrong repair. An alignment will not fix a dragging brake, and a brake job will not fix a bad tire. Here is how to tell which one you have before anybody puts it on a rack.
First, rule out the road
Almost every road is crowned, higher in the middle so water runs off. On a two-lane road that means your car sits on a slight left-to-right slope and will drift gently right if you let go of the wheel. That is the road, not the car.
The test is to find a flat stretch, an empty parking lot or the middle lane of a three-lane road, and try it there. If the drift disappears, you do not have a problem. If it persists on genuinely flat ground, keep reading.
When it pulls all the time: alignment or a tire
A steady pull that is there at every speed and whether or not you are braking narrows to two things.
Alignment
The angle that causes a pull is caster, and to a lesser extent camber. If one side has less caster than the other, the car wanders toward the lower side and does not want to return to center after a turn. Camber that is out on one side pulls toward the more positive side and also wears the shoulder of that tire.
Worth knowing: the angle people talk about most, toe, does not usually cause a pull. It destroys tires, quickly, and it makes the steering feel nervous, but a car can be badly out on toe and still track straight.
A tire
Tires can pull on their own, from a belt that has shifted inside the carcass or simply from how the tire was built. This is more common than people expect and it is the reason a good shop tries the cheap test first: swap the two front tires side to side. If the pull changes direction, the problem is a tire and no amount of alignment will fix it. If the pull stays exactly where it was, it is the car.
That swap takes ten minutes and it is the difference between a tire and a suspension repair.
When it pulls only under braking: the brakes
If the car tracks straight until you touch the pedal and then dives to one side, that is not alignment. One front corner is doing more work than the other, and there are three usual causes.
- A sticking caliper slide pin. The caliper cannot release cleanly, so that corner drags slightly all the time and grabs harder when you brake. Often accompanied by a hot wheel and a smell after a short drive.
- A collapsed brake hose. The rubber has failed internally and acts as a one-way valve, holding pressure at that caliper. It is a small part and an easy repair, and it is invisible from outside.
- Uneven pad or rotor condition. One side glazed, contaminated with fluid, or worn considerably further than the other.
Any of these will also chew through that corner's pads and rotor, so a braking pull is worth chasing promptly rather than living with.
When it wanders rather than pulls
A pull is consistent. Wandering is different: the car will not hold a line, needs constant small corrections, and feels vague on the freeway. That points at play rather than geometry. Worn tie rod ends, a tired steering rack, collapsed control arm bushings or a worn wheel bearing all produce it, and all of them are found by loading each joint on a lift rather than by looking at an alignment printout.
This also matters in the other direction: if something is worn, an alignment will not hold. The rack pulls the numbers into spec, the worn part moves again on the first pothole, and you are back where you started with a bill. A shop that inspects the front end before aligning it is doing you a favor, not upselling you.
The steering wheel is off center but the car goes straight
A specific one, and it usually points at the rear of the car. The rear axle sets the line the front has to steer to. If the rear is pointing slightly off the vehicle's centerline, the only way to drive straight is with the wheel held off center. Adjusting the front to compensate makes the wheel look right and leaves the car crabbing down the road.
The reading that catches it is thrust angle, and it is on every four-wheel alignment printout. If somebody offers you a front-end alignment on a car with this symptom, ask about the rear.
What causes it here
Michigan roads do most of this. A pothole on Woodward in March delivers a sharp impact straight into the steering and suspension, and the damage is not always dramatic. Bent steering components and shifted subframes happen, but far more often it is simply the geometry moving a fraction of a degree, which is enough to scrub a set of tires in a season.
Two other causes worth naming. Any suspension work moves alignment, whether anybody intended it to, which is why a strut or control arm replacement should be followed by an alignment. And a lift, larger tires or lowering springs change the geometry by design, so a modified vehicle needs setting up rather than resetting.
Getting an answer rather than a guess
The order we work in is inspection, then measurement, then adjustment. Tires and pressures checked and equalised first, because uneven pressures change the readings. Then tie rods, ball joints, bushings and bearings loaded and checked for play. Then all three angles on all four corners against the manufacturer's spec, with the before reading printed so you can see what was actually wrong.
If the answer is that nothing is out, we will tell you that and look at the brakes and the tires instead. A pull has a cause, and the useful thing is finding which one it is rather than buying the most likely repair.