Did you just get your new pump but it's reading different than others? Thats okay! Thats normal! When we tested pumps (roughly 10-15 other models) there was A HUGE DIFFERENCE in all of their readings. You just need to adjust using your pump to your daily use. Feeling for tire pressure after each use is always a great next step.
Bike pump gauges can sometimes show pressure that doesn’t perfectly match other gauges, and there are a few scientific reasons for this. Here’s a clear breakdown of what’s happening:
• The gauge measures pressure in the pump system, not just the tire.
When you attach the pump, some air from the tire fills the hose and gauge chamber. This briefly lowers the tire’s pressure, and the gauge reads the combined system pressure. This effect is more noticeable on narrow road tires with small air volume.
• Mechanical gauges have built-in accuracy limits.
Most pump gauges use a Bourdon-tube mechanism—a curved metal tube that straightens as pressure increases. These are durable and reliable, but they typically have a ±2–5% accuracy range. At 100 psi, even a 3% tolerance means the reading could be off by ±3 psi.
• High-range gauges are less precise at low pressures.
Because pumps often measure up to 150–200 psi, the gauge scale has wide increments. That means small pressure differences (especially in MTB or gravel ranges like 20–40 psi) aren’t measured with fine accuracy. A 2–3 psi error is normal and within spec.
• Seal quality and clogged sealant affects the reading.
If the pump head doesn’t make a perfect airtight seal, the gauge can show fluctuations or slightly lower readings. Even microscopic leakage can influence the pressure inside the pump barrel.
For more accurate reading, clean out all the sealant from the valve if clogged.
• Air compression and volume differences matter.
Road tires have low volume and high pressure, so adding the pump hose volume has a bigger percentage effect.
MTB tires have high volume and low pressure, so the hose makes almost no noticeable difference.
• Vibration and impacts cause “gauge drift.”
Over time, pumps get knocked over, dropped, or thrown in cars. These impacts can make the Bourdon tube or internal linkage shift slightly, causing readings to drift even though the pump still works normally.
• Pumps prioritize durability over laboratory precision.
Pump gauges are designed to survive years of use, not to function like precision instruments. They’re reliable for general inflation, but not meant to match the accuracy of standalone digital gauges.
For the most accurate results, we recommend inflating slightly above your target pressure using your pump, then checking your tire with a separate digital gauge and making small adjustments as needed.
Want even more information? Check out this cool article:
https://www.outridercomponents.com/blogs/news/how-accurate-are-pump-pressure-gauges