Both Edge Tread Wear: Underinflation or Camber?

Read the pattern first

Both-edge wear means the shoulder ribs on both sides of the tread are shorter than the center ribs. It is one of the clearest signs of low inflation pressure. A tire contains the air that sustains the vehicle's load, and when that air is below the recommended level, the tire flexes more and the center of the tread carries less of the contact patch. The shoulders then do more work and wear faster.

Some drivers suspect camber when they see edge wear, but camber is a one-shoulder problem. Camber tilts the wheel, loading the inside or outside shoulder of that tire. To get even stripes on both edges of the same tire, you need an inflation issue, not a wheel-angle issue.

Why underinflation wears both shoulders

The federal safety standard for radial tires describes the tread as the part of the tire that contacts the road and a tread rib as a section running around the tire. The outer tread ribs are the ones that feel low pressure first. When the tire is low, the footprint becomes longer and the shoulders are forced against the pavement while the center lifts slightly. That repeated scrubbing wears the two shoulder ribs down together.

Keeping tires at the recommended pressure is also a fuel economy and safety step. The U.S. Department of Energy points out that properly inflated tires are safer and last longer. The right pressure is listed on the vehicle placard, often in the driver's door jamb, not the maximum number on the tire sidewall. For more on setting pressure, see tire pressure basics and inflation pressure charts.

When camber is the cause

Camber is the tilt of the wheel when viewed from the front. If the top of the tire leans inward, negative camber, the inner shoulder carries more load. If the top leans outward, positive camber, the outer shoulder carries more load. Because of that, camber leaves a one-sided wear stripe on the affected tire. Both tires on an axle can show camber wear, but each tire will be worn on one shoulder, not on both edges.

To tell the difference, look at both shoulders of each tire. Underinflation wears the inside and outside edges at the same time. Camber wear is usually confined to one side of a tire. If the tire still shows both-edge wear after pressure is correct, have a technician check the camber and alignment. An alignment check will also reveal toe and suspension angles.

Other suspension and alignment causes

Toe, the angle of the tires relative to the direction of travel, can also wear edges. Too much toe-in or toe-out makes the tread scrub sideways, but it often leaves a feathered edge rather than a clean strip on both shoulders. Worn ball joints, bushings, or wheel bearings can change how the tire meets the road and make uneven wear worse. If pressure is correct and both edges are still wearing, inspect the suspension before buying new tires.

The Tire Industry Association, which trains tire technicians, makes inspection the first step in tire safety. A trained eye can separate a pressure problem from an alignment problem by looking at the whole tire, including the opposite tire on the same axle. For a broader look, see shoulder wear causes and the wear diagnosis chart.

How to correct it and keep it from coming back

Correct both-edge wear by setting every tire to the vehicle manufacturer's recommended cold inflation pressure. Check the pressure when the tires are cold, before driving, using a gauge. Do not target the maximum pressure molded into the sidewall; that figure describes the tire's maximum permissible inflation pressure, not the pressure your vehicle needs.

On many vehicles, the tire pressure monitoring light is a safety backup. Federal TPMS rules require the warning when one or more tires is 25 percent below the recommended cold pressure. That is already a serious drop, so do not wait for the light. Regular checks prevent the low-pressure condition that causes both-edge wear. If a tire keeps losing pressure, find the leak before it ruins another set of tires.

Inspect the tread and use the treadwear indicators molded in the principal grooves. When the surface wears down to those bars, the tire has reached the worn-out point and should be replaced. A tire that is also underinflated will often show those indicators sooner on the shoulder ribs than in the center.

Replacement should match the vehicle's size and load rating. The federal tire selection standard requires that tires fitted to an axle have load ratings suitable for the axle's rating. A tire that matches the vehicle will wear more evenly once the pressure is correct. If you had underinflation damage, check whether the worn set can be repaired or whether replacement is the safer choice.

What to look for in replacement tires

When you replace tires, choose a type that fits your driving. For cars and crossovers in mixed conditions, all-season tires are a common fit. If you drive a truck or heavy SUV, light truck tires may be required for the load. In snow country, winter tires give better cold-weather traction, while summer tires suit warm, dry driving.

The most important fix for both-edge wear is still correct inflation from the day the new tires are mounted. No tread design or compound can overcome a tire that is consistently run below the vehicle's recommended pressure.

What to pick for your use

Questions

Can camber cause wear on both edges of the same tire?

Not in the usual sense. Camber tilts the wheel so one shoulder of that tire carries more load. Both-edge wear on the same tire is far more likely to come from underinflation.

How can I tell underinflation wear from camber wear?

Underinflation produces a matching stripe on both outer tread ribs while the center still has more tread. Camber wear appears on one shoulder, either the inside or the outside. Check pressure before assuming alignment is wrong.

What pressure should I use?

Use the vehicle manufacturer's recommended cold inflation pressure from the door placard or owner's manual. The maximum pressure printed on the tire sidewall is not the target for normal driving. Check the pressure before driving, when the tires are cold.

Will the tire pressure light catch underinflation before the tire wears?

The TPMS warning is a safety threshold, not a maintenance reminder. Federal rules trigger the light at 25 percent below the recommended cold pressure. By that point the tire has already been running low, so check pressure regularly on your own.

If both edges are worn, do I need an alignment?

Start with inflation and load. If the pressure is correct and the tires still wear on both edges, have the suspension and alignment inspected. Toe, worn parts, and camber can affect edge wear, but the most common cause is low pressure.