Alignment, balance, and TPMS

What alignment actually sets

A typical alignment sets three angles. Toe is the direction the tires point relative to each other, slightly in or slightly out when viewed from above. Toe is the setting that most quickly saws tread into a feathered edge you can feel with your hand. Camber is the inward or outward tilt of the tire viewed from the front. Too much tilt wears one shoulder. Caster is the fore-aft tilt of the steering axis. It affects how firmly the steering returns to center on the freeway more than it writes a wear pattern.

Phoenix roads are hard on these settings. Expansion joints, washboard at the edge of a construction zone, and the occasional curb strike knock toe out of spec. A truck that tracks straight on a smooth morning can still be wearing the inner shoulder if camber is off. You will not always feel it before the tire shows it. When you replace tires, look at the old set. Feathering, a shoulder gone on one side, or cupping is the case for an alignment before the new tread is ruined the same way.

When a wheel change makes alignment part of the job

Any change in offset or wheel width moves the tire relative to the suspension. The truck may still be inside the adjustment range, or a camber bolt may now be required, or the tire may rub before alignment can help. Alignment cannot create clearance that the fender does not have. It can put the angles back where the manufacturer put them so the new tire size wears evenly.

Replacing tires with the same size on undamaged wheels does not always require an alignment if the old tires wore evenly and the steering wheel sits straight. It is still reasonable if it has been more than a year or two, or if you cannot remember the last measurement. Replacing a bent alloy or steel wheel should include a check that the new wheel is round. Aligning a truck with a bent wheel hides the bend for about as long as the new tire's shoulder lasts.

Balance is the other half of a smooth freeway

Balance corrects heavy spots so the tire and wheel do not hop or shake as speed rises. A vibration that starts around 60 or 70 mph on the Loop 101 and fades when you slow down is often balance, a bent wheel, or a tire with a broken belt, not toe. Road-force balancing can catch a tire that is round enough for a normal spin balance and still harsh on the road. Ask for it if a new set shakes and a standard balance did not fix it.

A tire that is wearing in cups, a scalloped pattern around the shoulder, can be a shock or strut that no longer controls the wheel, especially on a truck that has hauled weight for years. Balance will not revive a dead damper. If the old tires are cupped, mention it when you buy the new ones so you are not blaming the tread.

TPMS after the tires are mounted

A direct tire-pressure system uses a sensor in each wheel, usually at the valve stem. Sensors have batteries that die, and they can be broken by a tire machine if the technician is careless. After new tires or a sensor replacement, the vehicle often needs a relearn so it knows which sensor sits at which corner. The procedure may be a dash menu, a sequence with the ignition, or a tool the shop owns. Until that relearn is done, the warning light can stay on even at the correct cold pressure.

An indirect system uses the anti-lock brake sensors to notice a wheel turning faster than the others, which is what a smaller, underinflated tire does. It has no valve-stem sensor to replace, but it still needs a reset after you set pressures so it learns the new normal. Neither system measures tread age or alignment. They are pressure watches. A light that returns every cool morning is telling you the cold set point is low, which the pressure guide covers.

Align and balance so the tire wears evenly and the steering stays quiet. Set cold pressure so the carcass does not overheat. TPMS only reports the pressure problem later.