The most expensive alignment mistake is adjusting around a mechanical defect. A disciplined pre-alignment inspection protects measurement accuracy, prevents repeat work and gives the technician evidence for repairs that must be completed before adjustment.
Inspect before installing targets or beginning compensation.
Tire condition can explain a complaint even when alignment values are acceptable.
Looseness and binding are equally important.
The lift, turn plates and rear slip plates are part of the measurement system.
Start with the customer concern
Ask when the condition occurs: at constant speed, during braking, under acceleration, after a tire change, on one road or on every road. Note whether the concern is pull, drift, steering-wheel position, instability, vibration or tire wear. These are different symptoms and do not point to the same cause.
Record the tire positions and visible wear before rotation or pressure correction. Once the tires are moved or inflated, some diagnostic evidence is lost.
Tires and wheels
| Check | What to look for | Why it matters |
|---|---|---|
| Pressure | Side-to-side difference, placard value, obvious leakage | Changes rolling radius, tire force and ride height. |
| Tread wear | Feathering, one-edge wear, cupping, diagonal wear | Provides history of geometry, damping and rotation practices. |
| Tire construction | Matching size, type, load and direction | Mixed tires can create pull or stability concerns. |
| Wheel condition | Bent rim, damage, missing hardware | Can affect compensation and wheel direction. |
| Mounting | Correct seating and torque | Prevents false movement and safety risks. |
Steering and suspension
Check for free play with the suspension loaded and unloaded as appropriate. Tie-rod ends, ball joints, control-arm bushings, wheel bearings, steering-rack mounts and strut attachments can all allow the wheel to move after adjustment. A component can also bind without being loose, preventing the suspension or steering from returning to a repeatable position.
- Verify wheel bearings have no unacceptable play or roughness.
- Check tie rods and steering linkage for looseness and damaged boots.
- Inspect ball joints and control-arm bushings using the correct load position.
- Look for broken springs, leaking or damaged dampers and shifted spring seats.
- Inspect subframe location, collision marks and obviously bent components.
- Confirm steering linkage moves smoothly through the required sweep.
Ride height and load condition
Ride height determines the operating position of suspension links. A weak spring, incorrect spring, unequal load or air-suspension fault can change camber, caster and toe. Measure ride height at the locations specified by the vehicle manufacturer rather than comparing fender openings by eye.
Alignment-bay preparation
The alignment lift or rack must support the vehicle without twisting it. Turn plates and rear slip plates must be clean, free to move and unlocked at the correct stage. Bridges, stops and ramps must not contact the tires or suspension. The camera system must have a clear field of view and the vehicle must be positioned within its working range.
- Remove stones, rust flakes and debris from moving plates.
- Verify turn plates are centered before driving on.
- Confirm rear slip plates can move in the required directions.
- Check tire contact with ramps, stops and safety devices.
- Use the correct wheel chocks and lift locks.
- Confirm the lift is at the calibrated measurement position.
Decide whether to align, repair or diagnose further
Proceed with alignment when the vehicle is safe, the suspension is mechanically sound, the tires can support a meaningful road test and the measurement conditions can be met. Recommend repair first when looseness, damage or ride-height faults would prevent a stable adjustment. When the concern appears tire-related, record the condition and use a controlled tire-position test if appropriate.
This decision should be documented. A customer is more likely to understand a repair recommendation when the inspection findings, tire photos and initial alignment readings tell the same story.
Condensed pre-alignment checklist
Customer complaint recorded
Tire pressures and wear documented
Wheel and tire sizes verified
Steering and suspension inspected
Ride height and loading checked
Turn plates and slip plates free
Correct vehicle data selected
Road-test plan established
Frequently asked questions
Can toe be adjusted with a worn tie-rod end?
A reading can be moved on the screen, but it will not remain controlled under driving load. Repair the looseness before completing the alignment.
Should tire pressure be corrected before measurement?
Yes, after recording any meaningful imbalance related to the complaint. Use the vehicle placard or approved service information.
Is a road test required before every alignment?
A pre-test is valuable when safe and practical because it confirms the complaint. A final road test should verify steering-wheel position, returnability and directional behavior.
Technical content reviewed for TreadPlus Learn v1.0 · Updated July 16, 2026