Tire wear patterns take different forms, and the shape of the wear tells you which part of the vehicle is at fault. There are nine patterns worth knowing. Two come from incorrect inflation pressure, five from alignment or suspension faults, one from braking, and one is normal even wear. Read the pattern correctly and a tire replacement becomes a diagnosis.
Naming those patterns is the easy part. Catching them while the tire is still saleable is harder, because most uneven wear is too small to see. That is the problem we identified and with extensive research on all the different tire wear patterns, we developed TireBuddy and it has since run more than 100 million tire inspections worldwide.
Tire wear patterns chart
Use this chart to match what you see on the tread to its root cause. Wear location is the fastest diagnostic available in a service bay: center wear means pressure is too high, both shoulders means pressure is too low, one shoulder means alignment, repeating dips mean suspension, and a single bald spot means braking. Where the rubber is missing points directly at the system responsible.
| Pattern | What it looks like | Root cause |
|---|---|---|
| Center wear | Tread worn down the middle strip, outer ribs still deep | Over-inflation, contact patch shrinks to the center |
| Edge wear (both shoulders) | Both outer shoulders worn, center still deep | Under-inflation, sidewalls flex and load transfers to the shoulders |
| Camber wear (one side) | One shoulder worn, wear tapering evenly across the tread | Camber out of spec, the tire leans and rides on one edge |
| Toe wear | Depth loss on one shoulder, with a sawtooth edge on the tread blocks | Toe out of spec, the tire is dragged sideways as it rolls |
| Feathering | The sawtooth itself: blocks smooth on one edge, sharp on the other, before depth loss shows | The same toe error, caught earlier. Listed separately because it is what you detect first |
| Cupping (scalloping) | Scooped dips spaced several inches apart around the circumference | Worn dampers or loose suspension parts letting the tire bounce |
| Patch/spot wear | A single isolated flat bald spot | A locked wheel under braking, an ABS fault, or a lateral skid |
| Diagonal wear | Flat-spotted patches at an angle across the tread | Rear toe out of spec on a non-driven axle |
| Even wear (normal) | Uniform depth across all ribs, wear bars appearing together | Correct pressure and alignment, this is the target |
How to use the chart in a bay: run your palm across the tread in both directions before you reach for a gauge. Feathering and cupping identify themselves by feel long before they show up in a depth reading.
What are the different types of tire wear?
The nine types of tire wear are center wear, edge or shoulder wear, camber wear, toe wear, feathering, cupping, patch wear, diagonal wear, and even wear. They divide into three groups by root cause: two come from inflation pressure, five from alignment and suspension faults, and one from braking. Even wear is the normal baseline.
Grouping them this way is faster in practice, because it tells you which system to check before you touch a gauge.
Alignment and suspension wear: camber wear, toe wear, feathering, cupping, and diagonal wear. These need a mechanical fix. Replacing the tire without correcting the fault destroys the new one on the same schedule.
1. Center wear
Center wear is tread loss concentrated down the middle of the tire while the outer ribs stay deep. The cause is over-inflation. Too much air rounds the tread profile, shrinks the contact patch to a narrow center strip, and forces that strip to carry the whole vehicle.
Set pressure to the figure on the driver’s door jamb placard, not the maximum stamped on the sidewall. The sidewall number is a structural limit, not a recommendation.
2. Edge wear (shoulder wear)
Edge wear is tread loss on both outer shoulders with the center still deep. The cause is under-inflation. Low pressure lets the sidewall flex, the tread bows away from the road in the middle, and the two shoulders carry the load.
Under-inflation also raises rolling resistance and running temperature, so edge wear frequently arrives alongside a heat-related failure risk. Check for a slow leak or a failed TPMS sensor rather than just topping the tire up.
3. Camber wear
Camber wear is tread loss on one shoulder only, tapering smoothly across the tread face. The cause is a camber angle out of specification: the wheel leans in or out at the top, so the tire rides on one edge instead of sitting flat.
Negative camber wears the inner shoulder and is the more commonly seen of the two, partly because most modern vehicles run some static negative camber by design. Positive camber wears the outer shoulder.
On independent suspensions, sagging springs and failed control-arm bushings pull the top of the wheel inward and drive camber further negative. On a solid or beam axle, sag and load do not change camber, so a one-sided pattern there points at a bent housing or at toe rather than at camber drift.
4. Toe wear
Toe wear is one-sided depth loss combined with a sawtooth edge on the individual tread blocks. The cause is a toe angle out of specification: the wheel points slightly in or out relative to straight ahead, so the tire is scrubbed sideways across the road on every rotation.
Toe wear and camber wear both produce one-sided wear, which is why they are confused. The distinguishing feature is the sawtooth. Camber wear leaves a smooth taper. Toe wear leaves an edge you can feel.
Which shoulder wears tells you the direction of the error. A feathered edge on the inboard side indicates excess toe-in; a feathered edge on the outboard side indicates toe-out.
5. Feathering
Feathering is the wear signature where each tread block is worn smooth on one edge and sharp on the other, so the tread feels smooth when you stroke it one way and rough the other way. The cause is a toe angle out of specification, sometimes amplified by a camber or caster change.
Feathering and toe wear are the same fault at two stages. Feathering is what the tread blocks do first; the one-sided depth loss called toe wear is what follows if the alignment is left uncorrected. Most technical sources treat feathering as the diagnostic signature of a toe error rather than as a distinct pattern, and Google’s own AI Overview for this topic lists feathering as the pattern with “toe alignment is wrong” as the cause.
The practical value is that feathering is detectable by hand in seconds, before it costs the customer a tire.
6. Cupping (scalloping)
Cupping is a series of scooped, dished-out dips spaced several inches apart around the circumference of the tire. The cause is vertical bounce: worn shock absorbers or loose suspension components let the tire lift and slam instead of holding steady contact, and the tread wears where it lands hardest.
The spacing is not a fixed figure. Bridgestone’s often-quoted description, as if someone scooped out tread “every three to four inches”, is an illustrative analogy, not a specification. Actual spacing depends on the suspension’s resonant frequency, the tire’s circumference, and the speeds the vehicle is driven at. Diagnose cupping on the repeating scooped shape, not on a measured interval.
Cupping is also called scalloping or choppy wear. A cupped tire produces a rhythmic droning noise that rises and falls with road speed, which is often what brings the vehicle in.
7. Patch wear and flat spotting
Patch wear is a single isolated bald spot on an otherwise healthy tread. The cause is a locked wheel under braking, a fault in the ABS, or a lateral skid. Unlike the alignment patterns, patch wear is a single event rather than gradual degradation.
Do not confuse patch wear with cupping. An isolated bald spot comes from a locked wheel. Multiple evenly repeating dips come from suspension bounce or imbalance.
Two kinds of flat spot, and only one is permanent. A tire that has stood parked for a long period develops a temporary flat spot from the tread taking a set; it disappears once the tire warms up and regains its shape on the road. A flat spot worn in by a locked wheel under braking is permanent, removes tread material, and renders the tire unserviceable. Find the brake or ABS fault before fitting the replacement.
8. Diagonal wear
Diagonal wear is a series of flat-spotted patches running at an angle across the tread face. The cause is almost always rear toe out of specification on a non-driven axle. It shows up most often on the rear tires of front-wheel-drive cars, minivans and SUVs with independent rear suspension, where the rear axle carries little load, does no driving, and its alignment is rarely checked.
Diagonal wear is frequently mistaken for cupping. The difference is orientation: cupping runs around the circumference, diagonal wear cuts across the tread.
9. Even wear and wear bars
Even wear is uniform tread depth across every rib, with the moulded wear bars appearing at the same time across the full width. This is the target condition and the sign that pressure and alignment are both correct.
Even wear is still wear. A tire wearing perfectly evenly still reaches the legal limit, and the wear bars are the built-in indicator that it has.
What causes tire cupping?
Tire cupping is caused by the tire bouncing rather than rolling in continuous contact with the road. Worn shock absorbers and struts are the most common source, because a damper that has lost its ability to control rebound lets the wheel oscillate vertically. The tread wears at each point of hardest contact, producing a regular, repeating pattern of dips.
Beyond dampers, the causes are:
- Worn or loose suspension parts, ball joints, tie rod ends, control-arm bushings and wheel bearings all introduce play that allows unwanted vertical or lateral movement.
- Wheel imbalance: an unbalanced assembly vibrates at a frequency tied to road speed, and the vibration prints itself into the tread.
- Radial or lateral runout: a bent wheel or an out-of-round tire produces the same effect as imbalance.
- Under-inflation combined with high load: a soft tire flexes more and is more easily set bouncing.
- Very low-profile or stiff-sidewall tires on a vehicle with tired dampers. A stiff sidewall has less compliance available to absorb the oscillation, so more of it reaches the tread.
Is tire cupping dangerous? Yes. A cupped tire has a reduced and inconsistent contact patch, which lengthens braking distances and degrades wet grip. It also signals a suspension fault that affects the vehicle’s ability to hold the road, so the tire is the symptom rather than the problem.
Can cupping be fixed? The wear itself is permanent. Once the dips are in the tread, they stay there, and the noise stays with them. Fixing the damper or suspension fault stops the pattern from progressing and protects the replacement tire, but the cupped tire has to come off.
Tire cupping vs feathering: how to tell them apart
Cupping shows as repeating scooped dips around the circumference of the tire and is caused by worn shocks or loose suspension letting the tire bounce. Feathering shows at the scale of a single tread block, smooth on one edge and sharp on the other, and is caused by a toe angle out of specification. Cupping you see and hear; feathering you feel.
Cupping produces dips large enough to see, repeating around the circumference of the tire, and comes from vertical bounce caused by worn dampers or loose suspension parts.
Feathering produces wear at the scale of a single tread block, smooth on one edge and sharp on the other, and comes from a toe angle out of specification.
| Cupping | Feathering | |
|---|---|---|
| Scale | Dips of several inches, repeating around the tire | Individual tread blocks |
| Direction | Runs around the circumference | Across each block’s leading edge |
| Detected by | Sight and a rhythmic droning noise | Running a palm across the tread both ways |
| Root cause | Shocks, struts, loose suspension, imbalance | Toe out of specification |
| Fix | Replace dampers or worn parts, then the tire | Reset toe, replace worn steering parts |
| Noise | Droning that rises and falls with speed | Usually silent |
A tire can carry both patterns at once. A vehicle with worn struts and an untouched alignment will cup and feather simultaneously.
How to read tire wear bars and tread wear indicators
Tread wear indicators, also called wear bars, are raised rubber ridges moulded into the base of the tread grooves at a height of 2/32 inch (1.6 mm). When the surrounding tread has worn down until it sits flush with those bars, the tire has reached the minimum legal depth across the EU and in most US states.
The US position is worth stating precisely, because it is often misreported. Federal regulation requires that wear indicators be moulded to show 1.6 mm; that is a construction requirement for the tire, not a nationwide in-use limit for the driver. Most states set 2/32 inch in use; California and Idaho work to 1/32 inch in any two adjacent grooves, and several states have no tread depth statute at all. Check the requirement for the state you operate in.
Wear bars are a pass/fail limit, not a measurement. They tell you the tire is finished. They cannot tell you how much life is left, and they cannot show uneven wear, because a bar flush on the inner shoulder and buried on the outer shoulder is exactly what a camber problem looks like, and a glance at one bar will miss it.
Read wear bars at three points across the tread and at three points around the circumference. A tire that is legal at the center and illegal at the shoulder is a tire that will fail an inspection.
Tread depth chart: when uneven wear means replace
Tread depth decides replacement. New passenger tires start at 10/32 to 11/32 inch (8.0 to 8.7 mm), with light-truck, all-terrain and winter fitments running deeper. The legal minimum is 2/32 inch (1.6 mm), but the practical replacement points come earlier: 4/32 inch for wet driving and 5/32 inch for snow. With uneven wear, the depth that decides replacement is the shallowest point on the tire.
| Depth (/32 in) | Depth (mm) | Condition |
|---|---|---|
| 10/32 – 11/32 | 8.0 – 8.7 | New (passenger) |
| 8/32 | 6.4 | Near new |
| 6/32 | 4.8 | Half worn |
| 5/32 | 4.0 | Winter limit |
| 4/32 | 3.2 | Wet limit |
| 3/32 | 2.4 | Marginal |
| 2/32 | 1.6 | Legally worn out |
| Below 2/32 | Below 1.6 | Illegal |
Notes on the thresholds:
- 2/32 inch (1.6 mm) is the legal minimum in most of the world. In the UK and EU, the requirement is 1.6 mm throughout a continuous band comprising the central three-quarters of the tread breadth, around the entire circumference, so a tire that is legal in one spot can still be illegal. In the US, the in-use limit is set per state, not federally.
- 4/32 inch is Tire Rack’s recommended replacement point for drivers expecting wet conditions, and 5/32 inch for snow.
- 3 mm is widely recommended in the UK as a replacement point rather than the 1.6 mm legal limit. This is genuinely contested: Michelin has argued publicly against a 3 mm rule because it discards usable tread and increases waste, while tire retailers and several safety organisations support it on wet-braking grounds. If you cite a 3 mm figure, present it as a recommendation with a named source, not as a requirement.
For uneven wear specifically, the depth that matters is the shallowest point, not the average. A tire measuring 6/32 at the center and 2/32 on the inner shoulder is a worn-out tire, and averaging the two hides that completely.
What does the treadwear rating (UTQG) tell you about wear?
The UTQG treadwear rating is a comparative number moulded into the sidewall that indicates how long a tire’s tread should last relative to a government reference standard set at 100. A tire graded 400 is projected to wear four times as slowly as that reference under test conditions. Grades are assigned in multiples of 20.
The test is run on a government-prescribed 400-mile loop near San Angelo, Texas. Convoys of test vehicles cover 7,200 miles in total, an 800-mile break-in plus sixteen 400-mile measured circuits; wear is measured against course monitoring tires, and the result is extrapolated to a full-life grade.
Two limits on how much the rating tells you:
- It is set by the manufacturer, not by a regulator. Each manufacturer grades its own tires against the reference. Comparing grades between two brands is unreliable; comparing two tires within one brand’s range is reasonable.
- The “multiply by 100 for expected mileage” rule has no basis. A 700-rated tire is not a 70,000-mile tire. Actual mileage depends on alignment, pressure, load, driving style, and climate, the same variables that produce the wear patterns in this article.
The other two UTQG grades on the sidewall:
| Grade type | Scale | What it measures |
|---|---|---|
| Traction | AA, A, B, C | Straight-line wet coefficient of friction. AA requires above 0.54 g on asphalt and 0.41 g on concrete; C is below 0.38 g and 0.26 g |
| Temperature | A, B, C | Heat resistance at speed. A is over 115 mph, B is 100–115 mph, C is 85–100 mph |
A high treadwear grade will not save a tire from a toe problem. Alignment beats compound every time.
How do you measure tire wear accurately?
Accurate tire wear measurement requires readings across the full tread width, not at a handful of points. Three gauge readings can check a tire against the legal limit, which is a pass/fail question. They cannot characterise a wear pattern, because uneven wear is the difference between the deepest and shallowest point across the tread, and on a 20 cm section that can be as small as 0.5 mm.
This is the structural weakness of manual inspection, and it is not a competence problem. A technician with a calibrated depth gauge who takes three readings across the tread is following standard practice. The method itself cannot resolve a 0.5 mm gradient, because it samples three points out of a continuous surface and the odds of landing on both the deepest and the shallowest are low.
Three consequences for a service operation:
- Uneven wear is found late. By the time three-point sampling detects a camber or toe pattern, the tire is usually unsalvageable, and so is the customer’s trust in the estimate.
- The finding is unevidenced. A number on a clipboard is an assertion. The customer never sees the tire, so a legitimate recommendation and an upsell look identical from where they are sitting.
- Results vary between technicians. Two techs measuring the same tire produce different numbers, which makes wear rate across visits impossible to trend.
The TireBuddy Tire Tread Scanner addresses the sampling problem directly. It is build with extensive research on the different wear patterns analysed through thousands of tire scans. The result: It measures 100,000 points across a 20 cm tread section in about five seconds from a smartphone, and returns a full-width profile rather than three numbers. Because it captures the full width, a one-sided pattern such as a camber taper appears as a shape rather than a set of readings a technician has to interpret.
For a service operation, that changes three things. Uneven wear is caught while the tire is still saleable and the alignment recommendation is still cheap. The customer sees a colour-coded map of their own tire rather than a number on a clipboard, making the conversation materially easier. And because every scan is stored, wear rate can be trended across visits, which turns tire replacement into a scheduled conversation rather than a surprise.
Tire Tread Depth Measurement on Mobile Phones
Inspect tire tread depth and wear with just a mobile phone. Integrate end-to-end digital tire checks into your existing inspection workflow with the TireBuddy app or ToolKit (SDK).
Frequently asked questions
What causes different wear on tires?
Different wear patterns come from different vehicle systems. Inflation pressure controls whether the center or the shoulders carry the load, producing center wear when over-inflated and edge wear when under-inflated. Alignment angles control whether the tire rides flat, producing camber and toe wear when out of specification. Suspension condition controls whether the tire stays in contact, producing cupping when it does not.
What is the 3% rule for tires?
The 3% rule states that a replacement tire’s overall diameter should stay within 3% of the original equipment size. Beyond that, speedometer and odometer readings drift, ABS and traction control reference speeds become inaccurate, and clearance to suspension components can be lost. It is a fitment guideline rather than a legal requirement, and it is unrelated to wear patterns.
Is 2.5 mm of tire tread OK?
2.5 mm is legal, since the UK and EU minimum is 1.6 mm, but it sits below the 3 mm replacement point many tires retailers and safety organisations recommend. At 2.5 mm wet braking distances are measurably longer than on new tires and aquaplaning resistance is reduced. For winter driving, 2.5 mm is below the 4 mm generally advised for winter tires.
What are the different types of tire tread?
Tread patterns fall into three designs. Symmetrical treads have the same pattern across the whole tire and can be rotated in any direction. Asymmetrical treads use different patterns on the inner and outer halves, with the outer half tuned for dry cornering. Directional treads are designed to rotate one way only, with the grooves angled specifically for water evacuation. No one of the three designs is inherently best in the wet; many of the highest wet-rated tires on the market are asymmetric. Tread design affects wear rate, but it does not cause the wear patterns in this article , those come from pressure, alignment and suspension.
How often should tire wear be checked?
Check tread depth and pressure at every service interval and at minimum once a month. Uneven wear develops over thousands of miles, so a monthly check catches a developing alignment fault while the tire is still saleable. Any vehicle that has hit a kerb hard, had suspension work, or carries variable loads should be checked more often.
Can you rotate tires to fix uneven wear?
No. Rotation distributes wear more evenly across a set of tires, which extends the life of the set, but it does not correct a pattern caused by an alignment or suspension fault. Rotating a tire with camber wear onto another corner moves the problem and starts a second wear pattern on the same tire. Correct the fault, then rotate.
