A bicycle tyre pressure and wear log: gauge readings and visual checks

What it is

A dated table with one row per check: the bicycle and wheel (front or rear), the tyre's printed identity (brand, model and size marking as printed), the pressure range printed on the sidewall copied verbatim with its units, the gauge used, the pressure read before any pumping, the ambient temperature if known, and a visual note in plain words (tread wear, cuts, cracks, embedded debris, sidewall discolouration) with a photograph of a marked spot. It records what a gauge and a look show; it decides nothing.

Why it matters

Pressure drifts between rides, and "I pumped it last week" is not a number. A log shows how quickly each tyre loses pressure, whether front and rear behave differently, and how wear progresses at one fixed spot, so that comparing two tyres becomes a comparison of rows rather than impressions.

How to apply

• Read the pressure with the same gauge every time and write the unit exactly as the gauge shows it (bar, psi or kPa). When a row has to be converted, use published factors: NIST SP 811 Appendix B.9 lists 1 bar = 100 kPa and 1 pound-force per square inch = 6.894 757 kPa. Keep the original reading next to the converted one.
• Mark a reference spot on each tyre (a paint dot near the valve) and photograph the tread there under the same light, so that wear is compared at one place across weeks.
• Log the reading before pumping and the value pumped to as two separate fields.
• Note conditions: days since the last check, distance ridden if you track it, where the bicycle was stored and at what temperature, and the time since the last ride.
• Report per tyre: the series of pre-pump readings, the pressure lost per day as arithmetic between consecutive rows, and the dated visual notes.

Pitfalls

Consumer gauges disagree with one another; a log is consistent within one gauge, not calibrated. The sidewall range is copied, not interpreted: this article gives no advice on which pressure to use, on whether a tyre is fit to ride or on repair. Air heard escaping while a gauge is attached means the reading is of a tyre that has just lost some; note it in the row. Noting the gauge and valve type (Presta or Schrader) helps a second reader judge the rows.