Identify Brake Inspection Positions, Measurements and Units

The short answer

A brake inspection sheet identifies each measurement by three things: a wheel position, the component being measured, and a unit. Position labels usually name a corner of the vehicle. LF is left front, RF is right front, LR is left rear and RR is right rear. Some sheets spell these out in full. Brake-lining thickness is commonly recorded in millimeters (mm). It sits in a different section from tire tread depth, which is often recorded in 32nds of an inch (/32), and from tire pressure, which is recorded in pounds per square inch (PSI). To transcribe a sheet accurately, copy each entry with its printed section, its printed position label and its original unit. Record which sheet and page it came from. Do not convert or merge values until you have confirmed what each label means on that particular form.

One condition changes how you use the numbers. An inspection sheet records what was measured. It does not tell you whether the measurement is acceptable. Minimum lining thickness and rotor limits come from the vehicle manufacturer's service information for the specific model, not from the layout of the form.

Key terms on a brake inspection sheet

• Axle position: whether a wheel is on the front axle or the rear axle. Most passenger-vehicle sheets combine this with side, which gives four corners.
• Left and right: conventionally taken from the driver's seat facing forward, so on a US-market vehicle left is the driver's side. Confirm the issuer's convention if the sheet does not state it.
• Brake lining: the friction material on a brake pad (disc brakes) or brake shoe (drum brakes). Its remaining thickness is the measurement most brake sections record.
• Rotor: the disc that the pads clamp against. Sheets may record rotor condition as a note or a check box rather than as a number.
• Inner and outer: on disc brakes, each wheel has a pad on each side of the rotor. Some sheets record them separately and others record one value per wheel.

How position labels appear on real templates

Two published blank templates show how much the layout can vary while the meaning stays the same.

Toyota's dealer multipoint inspection template (form TOYINSP-TXM, dated 06/09) uses abbreviated corner labels LF, RF, LR and RR for brake-lining entries, with the unit given as mm. Tire tread depth on the same form has its own /32 fields, and tire pressure has its own P.S.I. fields. The vehicle-information area at the top captures year, make and model, VIN and mileage.

European Coach Inc's pre-purchase inspection template writes the positions out in full in its Brake Inspection area: Left Front, Left Rear, Right Rear and Right Front. It provides mm entries, a place for rotor condition and space for comments. Tire and wheel information sits in separate areas of the form.

The row order differs between these two forms. Toyota's sequence runs LF, RF, LR, RR. The European Coach sequence runs Left Front, Left Rear, Right Rear, Right Front. If you copy values by row number from one sheet into a log built around another, you can assign a measurement to the wrong wheel. Always identify an entry by its printed label and never by its position in a list. These conventions belong to each issuer's own template and should not be assumed for any other shop's form.

Telling look-alike entries apart

The most common transcription error is merging measurements that share a position label but measure different things. A sheet can show LF in the brake section, the tread section and the pressure section, and each refers to a different component and unit. Use these cues to resolve which measurement you are looking at.

Cue	Brake lining	Tire tread depth	Tire pressure
Typical unit shown	mm	/32 (inch)	PSI
Section heading	Brakes, brake inspection, brake lining	Tires, tread depth	Tires, inflation, pressure
Same corner labels possible	Yes	Yes	Yes
Nearby notes	Rotor condition, comments	Wear pattern	Spare, if listed

If an entry has no unit written next to it, take the unit from the section's printed heading or column header. If neither shows one, record the value as unitless and flag it. Do not supply a unit by guessing from the size of the number. If a sheet uses a unit other than those above, record it exactly as printed rather than converting it.

What resolves an uncertain entry

• A legend or key on the sheet that defines its abbreviations.
• The section heading the value sits under, which tells you the component.
• A column or field header that states the unit.
• Whether the form separates inner and outer pads, or front and rear brake types, so you know whether one value covers a whole wheel.
• The issuing shop, if the sheet itself does not settle the question. Ask the shop which corner a label refers to or which component was measured, and note its answer and the date you received it.

Leave any detail the sheet does not state as unresolved in your record. For example, if a sheet gives one lining value per wheel, do not record it as the inner pad or the outer pad.

Transcribing entries into your own record

Keep the original sheet, either paper or PDF, and build a record that links every value back to it. A field layout like the following keeps each measurement tied to its source and its meaning.

Issuing shop:
Sheet identifier / date / page:
Vehicle (year, make, model, VIN, mileage as written on the sheet):
Printed section:
Printed position label:
Confirmed position:
Component (and inner/outer, if stated):
Reported value:
Original unit:
Issuer comment:
Unresolved question:
Confirmation reference (who confirmed, when):

• Copy the printed label exactly, such as LF or Left Front, before adding your interpretation in the confirmed-position field.
• Fill the confirmed-position field only after the sheet's legend or the issuer confirms the convention.
• Use one row per measurement. Never combine brake, tread and pressure values for the same corner into a single entry.
• Keep the unit with the number in every row, including when several sheets use the same unit.
• Copy shop comments word for word, such as rotor-condition notes, instead of summarizing them.

Worked example (hypothetical)

This example is illustrative and is not taken from a real inspection. Suppose a sheet shows "LF 6 mm" in its brake-lining section on page 1. Record the literal entry "LF 6 mm", the section name and the page number. Enter left front as the confirmed position only after you have checked how that issuer uses LF. Suppose the same page also shows "LF 7/32" in the tire section. Record that value as a separate tire tread entry with its own unit. It is not a second brake measurement. Neither figure tells you whether the brake or the tire is acceptable. That judgment requires the manufacturer's specification for the vehicle.

Next step

Once each value is logged with its label, unit and source page, you can compare readings for the same corner and component across inspections from different shops, even when their forms use different abbreviations or row orders. When you need to decide whether a reading calls for service, check the lining and rotor limits in the service information for your vehicle's model year, or ask the issuing shop which specification it measured against.