Tyre Dispatch · Workshop Data
Tread Pattern Direction
Tread patterns come in three architectures, and which one a tyre gets is decided almost entirely by the wheel it is wrapped around. Across 1,545 tyres that choice turns out to predict how the tread wears, which edge goes first, how much sidewall damage it collects - and it quietly removes the cheapest remedy for uneven wear from the tyres most likely to need it.
A symmetrical tread is the same across its width and the same in both halves. It can be fitted either way round and moved to any corner of the car. An asymmetrical tread runs a different pattern inboard and outboard - usually stiffer, blockier rubber on the outside for cornering and finer grooves inside for water - so it must be fitted the right way out. A directional tread is cut in a V and must rotate one way, so it can only move front-to-back on the same side of the car.
Those are engineering choices, but they are also constraints on the owner. We record the architecture of every tyre through the workshop alongside the measured tread, which lets us ask what each choice actually costs.
Figure 1 · The fleet
FINDING 01The wheel decides, not the driver
Tread architecture is not really a purchase decision. It is dictated by the size the vehicle takes.
Figure 2 · Pattern mix by sidewall profile
Asymmetric tread goes from 72% of ultra-low-profile tyres to 6% of high-profile ones. Rim diameter says the same: every one of our 38 R13 tyres is symmetrical, while 88% of R19s are asymmetric. And speed rating orders it almost perfectly.
Figure 3 · Pattern mix by speed rating
| Speed rating | n | Symmetrical | Asymmetrical | Directional |
|---|---|---|---|---|
| R - 170 km/h | 49 | 100% | 0% | 0% |
| S - 180 km/h | 101 | 98% | 2% | 0% |
| T - 190 km/h | 167 | 95% | 5% | 1% |
| H - 210 km/h | 452 | 80% | 19% | 1% |
| V - 240 km/h | 298 | 59% | 33% | 7% |
| W - 270 km/h | 308 | 16% | 76% | 8% |
| Y - 300 km/h | 80 | 0% | 95% | 5% |
The same split shows from the working end of the fleet. Every all-terrain tyre we have classified is symmetrical, as is 87% of mud-terrain rubber. Above load index 110 the fleet is 95% symmetrical. Tyres built to carry weight, work off-road or last a long time are symmetrical almost without exception - because they need to be rotatable, and because an asymmetric tread buys cornering grip that a working vehicle has no use for.
FINDING 02Asymmetric is taking over
Figure 4 · Asymmetric share by manufacturing era
Asymmetric tread has gone from 15% to 40% of the fleet in under a decade. Directional has gone the other way, from 9% before 2015 to 2% since 2022 - it is being squeezed out of general use and surviving in a niche we will come to.
This tracks the same shift our load-rating work found in Extra Load markings, and for the same reason: wheels have grown and profiles have shrunk. Asymmetric tread is what the industry fits to a big rim.
FINDING 03Asymmetric tyres wear the inside edge
This is the finding we did not expect, and it is the one worth acting on.
Our capture protocol records which way a tyre was oriented when measured. For asymmetric tyres the rule
is asym_inside_left - the inboard shoulder is measured first. That means we can ask a question
most tread data cannot: when an asymmetric tyre wears unevenly across its width, which side goes?
Figure 5 · Which edge wears, on protocol-tagged records
| Pattern | n | Inside edge lower | Outside edge lower | Mean inside − outside |
|---|---|---|---|---|
| Asymmetrical | 309 | 40% | 22% | −0.26 mm |
| Symmetrical | 472 | 21% | 31% | +0.06 mm |
| Directional | 24 | 29% | 25% | +0.04 mm |
Asymmetric tyres wear their inside edge nearly twice as often as their outside edge - 40% against 22% - and the effect strengthens with severity. Among asymmetric tyres with a gap wider than 1.0 mm between the two edges, 73% are worn on the inside.
The symmetrical control shows nothing: 21% against 31%, a mean of +0.06 mm, which is noise. The bias is specific to asymmetric tread.
That distinction matters. The pattern is not wearing the tyre out; it is a marker for a population of vehicles - lower, wider, more aggressively aligned - whose geometry eats inside shoulders. It also explains why our inflation report found asymmetric patterns carrying nearly double the alignment-wear rate: they are on the cars that have alignment faults.
FINDING 04The failure gap is mostly profile, not pattern
Asymmetric tyres fail a screening assessment far more often than symmetrical ones, and come off the car a year younger. It would be easy to blame the tread. We checked, and mostly it is not the tread.
Figure 6 · Outcome by pattern, before and after controlling for profile
| Pattern | n | Fail rate | Alignment wear | Median age | Median depth |
|---|---|---|---|---|---|
| Asymmetrical | 508 | 53% | 19% | 4.5 yrs | 2.90 mm |
| Directional | 68 | 48% | 6% | 6.5 yrs | 3.10 mm |
| Symmetrical | 969 | 41% | 11% | 5.5 yrs | 3.00 mm |
| Held within mid-profile only (aspect 60–65) | n | Fail rate | Alignment wear |
|---|---|---|---|
| Asymmetrical | 99 | 47% | 13% |
| Symmetrical | 503 | 41% | 11% |
Across the whole fleet asymmetric fails at 53% against symmetrical's 41%, and shows 19% alignment wear against 11%. Compare like with like, and both gaps shrink to almost nothing - 47% against 41%, and 13% against 11%. Roughly three quarters of the apparent penalty is really the low-profile, large-rim fitment that asymmetric tread happens to come on.
Directional tread is the interesting outlier: the lowest alignment-wear rate of any architecture at 6%, and the oldest at removal at 6.5 years. Directional tyres survive longest, because they end up on vehicles that are not being driven hard.
FINDING 05Asymmetric tyres collect more sidewall damage - and that one is real
One difference does survive the profile control, and it survives it cleanly.
Figure 7 · Sidewall cut rate, within matched profile bands
| Profile band | Pattern | n | Carrying a sidewall cut |
|---|---|---|---|
| Ultra-low (aspect ≤45) | Asymmetrical | 258 | 7.4% |
| Symmetrical | 63 | 3.2% | |
| Mid (aspect 60–65) | Asymmetrical | 99 | 3.0% |
| Symmetrical | 503 | 1.0% |
At both profiles, asymmetric tyres carry roughly two to three times the sidewall-cut rate of symmetric ones of the same shape. Ultra-low: 7.4% against 3.2%. Mid-profile: 3.0% against 1.0%. Profile alone does not explain it.
The likeliest reading is kerbing. Asymmetric tread marks a performance fitment, and performance fitments live on cars parked and driven closer to kerbs, often with a rim-protector rib that takes the hit. Whatever the mechanism, the association is consistent and it is not an artefact of tyre shape.
FINDING 06Directional tread has become a winter speciality
Directional patterns are 4.4% of the fleet and shrinking - 9% of pre-2015 tyres, 2% of those made since 2022. But they have not disappeared evenly.
Figure 8 · Where directional tread survives
| Group | n | Directional share |
|---|---|---|
| 3PMSF winter marked | 67 | 15% |
| Mud terrain | 55 | 13% |
| W-rated (270 km/h) | 308 | 8% |
| M+S only | 495 | 4% |
| No winter marking | 983 | 4% |
| All terrain | 131 | 0% |
Directional tread is nearly four times more common on properly certified winter tyres than on the fleet at large - 15% against 4%. That is exactly what the geometry is for: a V-shaped tread pumps water and slush outward from the centre as the wheel turns, which is worth the rotation restriction when the alternative is aquaplaning. It survives where it does real work, and it has retreated from everywhere else.
FINDING 07The rotation trap
Here is where the three findings above collide into something practical.
The tyres least able to be rotated are the ones that most need it
Rotation is the cheapest remedy in tyre maintenance. Move a tyre to a different corner and uneven wear gets a chance to even out; leave it where it is and the wear compounds until the tyre is finished.
A symmetrical tyre can go anywhere on the vehicle - any corner, either way round. An asymmetrical tyre must keep its outboard face outward, so it can cross sides but cannot be flipped. A directional tyre must keep turning the same way, so it can only move front-to-back on the same side unless it is dismounted and refitted.
Now set that against what we measured. Asymmetric tread is concentrated on ultra-low-profile, high-speed fitments. Those are the tyres showing the inside-edge camber wear in Figure 5, the highest alignment-wear rate in the fleet, and the shortest life at 4.5 years. They have the most uneven wear to correct and the fewest positions to correct it from. Symmetrical tread, which can be moved anywhere, mostly sits on mid and high-profile fitments that wear evenly and need it least.
None of this is an argument against asymmetric tread - it grips better, which is why it is fitted. It is an argument that an asymmetric fitment raises the value of the two things that are still available: rotating front-to-back on schedule, and getting the alignment checked. On a symmetric tyre a missed rotation is recoverable. On an asymmetric one, with a camber fault quietly eating the inside shoulder, it is not.
FINDING 08Asymmetric tread is not moulded flat
A final measurement, and a caution for anyone reading tread depths.
Figure 9 · Depth difference across the tread on genuinely unused tyres
| Pattern | Unused tyres measured | Centre deeper than shoulder by |
|---|---|---|
| Asymmetrical | 34 | 0.49 mm |
| Symmetrical | 25 | 0.37 mm |
New tread is not the same depth right across a tyre, and asymmetric tread is the more lopsided by design - 0.49 mm against 0.37 mm, with the shoulders moulded shallower in 55 of the 59 unused tyres we measured. That follows from what asymmetric tread is: a stiff, shallow outer shoulder paired with deeper inner grooves.
The practical consequence is that a half-millimetre difference across an asymmetric tyre may be how it left the factory, not evidence of a pressure problem. Our inflation work hit this directly: before we excluded unused tyres, 45.8% of them classified as under-inflated purely on their moulding. Anyone diagnosing wear from depth readings alone should know which architecture they are looking at.
Method, and what this cannot tell you
Records come from tyres documented at Tyre Dispatch between December 2025 and July 2026, chiefly tyres presented for replacement. Pattern architecture is classified at inspection from the tread face and the sidewall markings. Depth is taken at four positions across the width for most records and three for older ones.
The inside/outside analysis in Figure 5 uses only records carrying an explicit orientation protocol
- asym_inside_left, sym_dot_right or directional_forward. 899
records carry one, of which 805 also have a complete set of depth readings, and those 805 are what
Figure 5 reports. The 646 records captured before that field existed are excluded from that finding
entirely, because without a known orientation the order of the readings carries no directional meaning.
How well the direction markings are documented
Asymmetric and directional tyres carry markings that determine correct fitment - outside, inside, or a rotation arrow. We photograph those markings on 62% of asymmetric records and 50% of directional ones, and on 0% of symmetrical, which is correct since they have no fitment direction to record. Coverage is a capture priority rather than a finding about the tyres, but it bounds what this dataset could ever say about mis-fitting: we hold the marking, not the position it was fitted in, so nothing here establishes that any tyre was fitted the wrong way round.
Five limits worth stating plainly
- We never saw the vehicle. Camber, toe and rotation history are all inferred from the tyre. Figure 5 shows inside-edge wear; it does not prove a camber fault in any individual case.
- Pattern, profile, rim size and speed rating are not independent. They describe substantially the same performance fitment, which is why Findings 01 and 04 are best read together.
- We do not know fitted position or rotation history. Finding 07 argues from what rotation is geometrically possible, not from what was actually done.
- Directional is a small group. 68 records overall, 24 with an orientation protocol. The direction of its results is interesting; the precision is not.
- Fail rates are our own screening judgement, not certified warrant results, and describe tyres presented for replacement rather than a random sample of the fleet.
More from the research programme
The Workshop Tyre Report: First 1,500 Inspections · Tyre Research Hub · Tyre Pressures and Inflation Wear · Load Ratings and Load Capacity
Tyre Dispatch · New Zealand · First edition · 29 July 2026
Descriptive analysis of one workshop's records. Not a representative sample of the national fleet, and
not a substitute for a warrant of fitness inspection. Under the Land Transport Rule: Tyres and Wheels
2001, tyres on the same axle must be of the same size designation, construction and tread pattern type.
Corrections welcome:
email@tyredispatch.co.nz
Page © 2026 Tyre Dispatch NZ · Dataset, measurements and photographs © Taylor Houghton,
all rights reserved · Dataset licensing
