Bicycle Tire Pressure Calculator

Cold pump targets

Front {{ summaryWheels[0].pumpPsiDisplay }} / Rear {{ summaryWheels[1].pumpPsiDisplay }}

{{ summaryWheels[0].projectedRidePsiDisplay }} front · {{ summaryWheels[1].projectedRidePsiDisplay }} rear expected on-road

Check your inputs

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Riding category:

Pick the profile whose usual tire range matches your measured casing width.

System weight:

Enter total ride weight, then choose kg or lb in the same row.

Measured tire width:

Use calipers after inflation, e.g. 30.5 mm for a 700x30 tire.

Rim internal width:

Enter the internal rim width printed by the maker or measured between bead hooks.

Wheel size:

Select the diameter fitted to this tire, not a spare wheel size.

Surface:

Choose the roughest surface that will dominate the ride.

Ride feel:

Use Balanced for a neutral start; choose comfort or speed to bias the target.

Setup:

Select the setup mounted for this ride, including tube material when applicable.

Extra carried weight:

Enter only extra luggage or cargo not already counted above; use 0 otherwise.

Casing:

Choose supple, standard, reinforced, or insert-ready sidewalls.

Weather grip:

Leave Dry or mild unless the ride is wet/cold or hot pavement.

Load split:

Keep Auto unless you have a measured or well-known front load share.

Front load share: {{ front_load_percent }}%

Move 38%-52%; lower values mean more rear load and rear pressure.

Tire inserts:

Switch on only when foam inserts are installed in the wheels being ridden.

Inflation temp:

Enter -20 to 50°C for the place you inflate the tires.

°C

Ride temp:

Enter -20 to 50°C for the air temperature during the ride.

°C

Known minimum pressure:

Enter a psi floor or leave 0 to use the model's tire-width floor.

psi

Known maximum pressure:

Enter the lowest safe psi ceiling from tire/rim markings, or 0 for none.

psi

#	Wheel	Load	Pump	On-road	Ride window	Safe ride	Margin	Patch	Copy
{{ row.index }}	{{ row.wheel }} {{ row.note }}	{{ row.loadKgDisplay }} {{ row.loadLbDisplay }}	{{ row.pumpPsiDisplay }} {{ row.pumpBarDisplay }}	{{ row.projectedRidePsiDisplay }} {{ row.temperatureDeltaDisplay }}	{{ row.rideBandPsiDisplay }} {{ row.rideBandBarDisplay }}	{{ row.safeRideDisplay }} {{ row.safeRideBarDisplay }}	{{ row.marginDisplay }} {{ row.ceilingDisplay }}	{{ row.patchDisplay }} {{ row.patchLengthDisplay }}

Section	Item	Cue	Detail	Copy
Wheel tuning	{{ row.wheel }}	{{ row.header }}	{{ row.startText }} {{ row.lowerText }} {{ row.upperText }} {{ row.watchText }}
Setup check	{{ check.title }}	{{ check.short }}	{{ check.message }}

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Tire pressure is one of the few bicycle settings that changes how the bike rolls, grips, steers, and survives impacts on every ride. A pressure that feels fast on smooth pavement can bounce across chip seal, while a pressure that feels calm on loose gravel can squirm in a fast corner or let the rim strike a rock. The useful target is not a single universal PSI. It is a starting range for a specific rider, bike, tire, rim, surface, and setup.

The tire carries load by trapping air, shaping the casing, and pressing a contact patch into the ground. More load usually needs more pressure. More tire volume usually allows less pressure. A front tire and a rear tire usually do different jobs because the rear wheel often carries more weight, while the front wheel needs steering grip and predictable feedback. Cargo, a low aero position, suspension movement, and steep terrain can all change that split.

Sidewall markings are safety limits and size labels, not a complete pressure prescription. The measured inflated width can differ from the printed size because rim internal width changes the casing shape. Setup details matter too: tubeless tires, butyl tubes, latex tubes, tubulars, reinforced casings, supple casings, and tire inserts all change the tradeoff between support, puncture risk, comfort, and grip.

Bicycle tire pressure balances load, tire width, rim support, and contact patch size.

Common factors that change bicycle tire pressure
Factor	What usually changes	Why it matters
System load	Rider, bike, water, bags, tools, and cargo.	More load compresses the casing and raises the support pressure needed.
Tire volume	Measured casing width, wheel size, and rim internal width.	More volume can carry the same load at lower pressure with a larger contact patch.
Ride surface	Smooth road, broken pavement, gravel, roots, rocks, sand, or snow.	Rougher ground often rewards lower pressure for grip and less bouncing.
Setup limits	Tube type, tubeless, casing stiffness, inserts, rim design, and printed limits.	The tire and rim still set the hard safety boundary even when the ride feels good.

Temperature adds another wrinkle because a tire is a small air chamber. Air pressure rises when the tire warms and falls when it cools, so a tire pumped in a warm room can ride lower outside in cold weather. The change is usually small enough to tune, but it becomes noticeable when the garage and ride conditions are far apart.

A pressure estimate should be treated like a careful first test. Start inside the tire and rim limits, ride the actual surface, then adjust in small steps. Chatter, skipping, hand fatigue, or poor grip point toward a lower test pressure. Rim strikes, tire burping, casing squirm, or sidewall damage point toward more pressure, more tire volume, a stronger casing, or a different rim and tire match.

How to Use This Tool:

Enter the setup as it will be ridden, then compare the calculated front and rear targets with the limits printed by the tire, rim, or wheel maker.

Choose Riding category first. The category selects a baseline profile for road, all-road, gravel, mountain, utility, bikepacking, downhill, or indoor setups.
Enter System weight with the matching unit. Include the rider, bike, clothing, bottles, tools, bags, and any cargo that will be on the ride.
Use the inflated, measured casing width in Measured tire width. A sidewall label is useful, but the mounted width can change by several millimeters on a different rim.
Measure the mounted tire after inflation when possible; this width drives the load and contact-patch estimate more directly than the printed label.
Enter Rim internal width and select Wheel size. The calculator checks that the rim is narrower than the tire and adjusts the pressure for rim support.
Select Surface, Ride feel, and Setup. These choices bias the result toward speed, grip, comfort, loaded stability, tube protection, or tubeless support.
Open Advanced when the ride needs more detail: extra carried weight, casing stiffness, weather grip, manual front-load share, inserts, inflation and ride temperatures, or known pressure limits.
Fix any Check your inputs warning before trusting the targets. Common causes are nonpositive weight, rim width at or above tire width, temperatures outside -20°C to 50°C, or an inverted pressure limit.
Use Wheel Targets for the numbers to pump and Tune Notes for warnings about profile fit, rim match, temperature shift, load split, and equipment limits.

Interpreting Results:

Cold pump is the pressure to set where you inflate the tires. On-road is the pressure expected at the ride temperature. When both temperatures are the same, those numbers will be nearly identical. When the ride is much hotter or colder than the inflation location, the on-road pressure shifts according to the temperature correction.

The front and rear rows should be read separately. A higher rear target is normal when the rear wheel carries more load. A lower front target can improve steering grip, but it should still leave enough floor margin to avoid bottoming the tire on the rim. If the automatic load split does not match the bike, cargo position, or riding posture, switch to manual front-load share.

Ride window gives a practical adjustment band around the projected on-road target.
Safe ride shows the modeled ride-pressure floor and ceiling after tire width, setup, and rim match are considered.
Margin shows how much room remains above the floor and below the ceiling.
Patch estimates contact patch area from wheel load and projected ride pressure.
Pressure Load Curves shows how cold and expected ride pressure change across nearby system weights.

Use the ride window as a tuning range, not as a promise that every pressure in the range is safe for every tire and rim. A tubeless gravel setup on a wide rim can often explore the lower side of the window. A narrow road tire with a butyl tube usually needs more caution near the floor because pinch-flat and rim-impact risk rises quickly.

The export buttons copy or download the current targets, tune notes, chart data, or JSON payload for setup notes and ride logs. Recheck the calculation after changing tires, adding luggage, swapping wheels, moving from tubes to tubeless, or riding a surface that is rougher than expected.

Technical Details:

The pressure model starts with wheel load and measured tire width. Wheel load comes from total system weight and the selected or manual front-load share. Tire width is the working proxy for air volume and casing footprint, so wider tires produce lower pressure for the same modeled load. Category, wheel size, surface, ride feel, setup, casing, weather, rim ratio, and inserts then move the baseline up or down.

The combined setup multiplier is bounded before it is applied. That keeps an extreme stack of settings from pushing the result outside the supported range. The final riding pressure is then clamped to modeled floor and ceiling limits based mainly on tire width, setup, and rim-to-tire relationship. User-entered minimum and maximum limits are applied to the cold pump target, which is the pressure most riders can actually set with a pump gauge.

Formula Core:

The wheel target begins with load per wheel, measured casing width, and a baseline coefficient, then applies profile and setup factors before the pressure is constrained to the modeled ride range.

{PSI}_{ride} = clamp (\frac{L_{kg} \times 52.5}{W_{mm}} \times F_{profile} \times F_{setup}, {PSI}_{min}, {PSI}_{max})

Temperature conversion uses absolute pressure, not gauge pressure alone. Gauge PSI is converted by adding atmospheric pressure, scaled by the ratio of absolute temperatures in kelvins, then converted back to gauge PSI.

{PSI}_{to} = (({PSI}_{from} + 14.6959) \times \frac{T_{to} + 273.15}{T_{from} + 273.15}) - 14.6959

Bicycle tire pressure variables
Variable	Meaning	Result effect
`L`	Load on one wheel, calculated from system weight and front or rear load share.	Higher wheel load raises pressure.
`W`	Measured inflated tire width in millimeters.	Wider tires lower pressure for the same load.
`F_profile`	Riding category and wheel-size adjustment.	Adapts the baseline for road, gravel, MTB, utility, cargo, or indoor use.
`F_setup`	Surface, ride feel, tube or tubeless setup, casing, weather, rim ratio, and inserts.	Moves the target toward grip, comfort, protection, or firmness.
`clamp`	Modeled pressure floor and ceiling, plus any user-entered cold pressure limits.	Prevents a displayed target from leaving the supported pressure band.

Modeled ride-pressure bounds by measured tire width
Measured tire width	Modeled floor before setup changes	Modeled ceiling before rim and tube changes
28 mm or narrower	55 psi	110 psi
29-32 mm	45 psi	95 psi
33-40 mm	34 psi	78 psi
41-50 mm	26 psi	65 psi
51-62 mm	20 psi	48 psi
Wider than 62 mm	18 psi	42 psi

Tubeless setup and inserts lower the modeled floor because they reduce pinch-flat risk. A butyl tube slightly raises the modeled ceiling because the calculator treats it as a setup that may need more support. A narrow rim relative to tire width raises the target because the casing has less sidewall support, while a very wide rim can lower the target but also narrows the practical margin before harshness, burping, or compatibility limits become important.

Bicycle tire pressure setup tendencies
Input	Lower-pressure tendency	Higher-pressure tendency
`Surface`	Broken pavement, loose gravel, roots, rocks, mud, sand, or snow.	Smooth tarmac, track use, trainer use, or high-speed road riding.
`Ride feel`	Comfort, grip, or loaded stability.	Fast support, sprint support, or a firmer aero feel.
`Setup`	Tubeless and inserts can support a lower starting point.	Butyl tubes usually need more protection against pinch flats.
`Casing`	Supple or light casings.	Reinforced, double-ply, insert-ready, or thick sidewalls.
`Weather grip`	Wet or cold conditions where grip reserve matters.	Hot pavement where the rider may prefer firmer support.

Contact patch is estimated by dividing wheel load in pounds by projected ride pressure in PSI, then converting square inches to square centimeters. The displayed patch length is a simple area-to-width estimate, not a tire-footprint measurement from a laboratory drum. It is most useful for comparing front versus rear load, or for seeing how much a pressure change alters the modeled footprint.

Limitations, Privacy, and Accuracy Notes:

Pressure calculators cannot know the exact casing stiffness, tread shape, bead fit, rim bed design, tire wear, sealant behavior, wheel damage, or rider technique. Manufacturer tire and rim markings still take priority, especially for hookless or tubeless straight-side rims where tire type and maximum pressure compatibility are critical.

The calculation runs in the browser from the values currently entered on the page. The visible exports are generated from those values for copying or downloading. No account, location, or ride history is needed to calculate the pressure target.

Use the result as a first test, then tune one wheel at a time in small steps. Stop lowering pressure if you feel rim strikes, tire squirm, casing roll, or burping. Stop raising pressure if the bike skips across rough ground, loses grip, or exceeds the lowest printed limit from the tire, rim, or wheel system.

Worked Examples:

An endurance road setup with an 82 kg system weight, 30 mm measured tires, 21 mm internal rims, 700C wheels, tubeless setup, normal pavement, and equal inflation and ride temperature produces separate front and rear targets. With the automatic all-road load split, the front wheel carries about 36.9 kg and the rear about 45.1 kg. The modeled cold pump targets are about 58.9 psi front and 72.0 psi rear, with the rear higher because it carries more load.

A loaded bikepacking gravel setup behaves very differently. A 105 kg system weight on 50 mm tires, 25 mm internal rims, 650B wheels, tubeless setup, inserts, hardpack terrain, and loaded-stability ride feel gives a much lower starting point. If the tires are pumped at 10°C and ridden at 25°C, the cold pump targets are about 25.9 psi front and 30.5 psi rear, rising on the ride to about 28.0 psi front and 32.9 psi rear.

Those examples are not recommendations for every rider with similar tire sizes. They show how load, tire volume, surface, setup, and temperature interact. Changing one important detail, such as switching from tubeless to butyl tubes or adding a rear rack bag, can move the target enough to justify another calculation.

FAQ:

Should I use the pressure printed on the tire sidewall?

The printed range is a safety and compatibility boundary. Use it to cap the result, then tune within the allowed range. If the tire, rim, and wheel each provide a maximum, follow the lowest one.

Why does measured tire width matter more than the label?

A tire labeled 30 mm can measure wider or narrower after mounting because rim internal width changes the casing shape. The inflated measured width better reflects the actual air volume and support available on the bike.

Why are the front and rear pressures different?

The wheels usually carry different load shares. Rear pressure often rises because the rear wheel carries more system weight, while the front can stay slightly lower for grip and steering feel when there is enough support margin.

Can I use the same result for tubes and tubeless?

No. The setup choice changes the pressure model because tube type, pinch-flat risk, tubeless bead behavior, and inserts affect how low the tire can be tested safely.

Why does temperature change the pump target?

The tire is a mostly fixed-volume air chamber. If the air inside warms up, pressure rises. If it cools, pressure falls. The cold pump target accounts for the entered inflation and ride temperatures so the expected on-road value lands near the riding target.

Glossary:

Cold pump: The pressure to set before the ride at the inflation temperature.
On-road pressure: The projected pressure after the tire air changes to the ride temperature.
Ride window: A small tuning band around the projected on-road target.
Rim internal width: The bead-seat width inside the rim, measured between the inner rim walls.
Load split: The percentage of total system weight carried by the front and rear wheels.
Contact patch: The estimated ground-contact area carrying the wheel load at the projected ride pressure.