---
title: "Bike Tire Pressure Calculator (PSI & Bar) | Rapid Rambler"
description: "What psi for 700x28 or gravel tires? Front and rear pressure for your weight and tire width from published charts, capped at your tire and rim maximum."
url: https://rapidrambler.me/bike-tire-pressure-calculator/
---

15% tire drop · psi and bar · front and rear

# Bike tire pressure calculator

**What psi for 700×28?** For a 75 kg rider on a 10 kg road bike, Frank Berto’s 15% tire-drop chart gives about **54 psi (3.8 bar) front and 84 psi (5.8 bar) rear**. Lighter riders need less, heavier riders more, and wider tires much less. Enter your own weight, tire width and surface below. The answer is never higher than the maximum printed on your tire or rim.

## How the calculator picks a pressure

There is no single correct pressure, but there is a well-tested starting point. Frank Berto measured how far dozens of tires squash under load and charted the pressure that gives a **15% tire drop**: the tire’s height shrinks by 15% when you sit on the bike. Bicycle Quarterly printed his chart in Jan Heine’s article “Optimizing Your Tire Pressure for Your Weight”, after finding that the pressure where its own tire tests stopped getting faster corresponded roughly to that 15% drop. Higher pressures made the bike no faster, only harsher. The 15% figure itself is the drop several tire makers recommended.

Tire drop, after the cross-section drawing in Bicycle Quarterly’s article (redrawn).

The chart works per wheel, not per bike. Your rear wheel carries more of the load than the front, so it needs more air. Bicycle Quarterly measured typical splits: a racing bike carries about 40% on the front and 60% on the rear, a randonneur bike with a front bag 45/55, and a city bike with a loaded rear rack 35/65. The calculator multiplies your total weight (you, the bike and anything you carry) by your split to get each wheel’s load, then reads Berto’s line for your width. For widths between the chart’s lines (20, 23, 25, 28, 32 and 37 mm) it reads between the two nearest lines.

### Quick reference: road tires, 40/60 split

Front / rear psi from Berto’s chart for a road bike. “≤” marks a wheel lighter than the chart’s lowest load, so the chart’s edge value is the most you need.

| Rider + bike | 700×25c | 700×28c | 700×32c |
| --- | --- | --- | --- |
| 60 kg (132 lb) | ≤48 / 68 | ≤42 / 58 | ≤33 / 45 |
| 70 kg (154 lb) | 50 / 80 | 44 / 68 | 35 / 53 |
| 80 kg (176 lb) | 59 / 93 | 51 / 79 | 40 / 61 |
| 90 kg (198 lb) | 68 / 106 | 58 / 89 | 45 / 69 |
| 100 kg (220 lb) | 76 / 119 | 65 / 99 | 51 / 77 |
| 110 kg (243 lb) | 85 / 132 | 72 / 110 | 56 / 85 |

## Gravel tire pressure

Berto’s chart stops at 37 mm. For gravel the calculator switches to Michelin’s published gravel and cyclocross table, which gives one pressure for both tires by rider weight band, for 33, 35, 40 and 47 mm tires. A 71–80 kg rider on 40 mm tires starts at 3.0 bar (43.5 psi); on 47 mm tires, 2.4 bar (34.8 psi). Michelin notes that rougher terrain calls for slightly lower pressure within the recommended range, and that tubeless setups can run lower because there is no inner tube to pinch. Bicycle Quarterly makes the same point from its testing: on gravel you can run lower pressures than on pavement. If you ride 38–47 mm tires on smooth roads, the calculator still uses Michelin’s table (the nearest published chart) and says so.

## The maximum is a hard limit

Every tire has a maximum pressure moulded on the sidewall, and some rims have one too. The calculator never suggests more than the lower of the two, and tells you when the chart wanted more. That usually means the tire is too narrow for the load, and a wider tire is the fix, as Bicycle Quarterly also advises for heavy riders and bikes.

**Hookless rims** (tubeless straight-side, “TSS” in the ETRTO standard) hold the tire without a hooked lip, so they have low pressure limits that depend on the tire. Schwalbe, which requires rims built to the ETRTO hookless standard, publishes these maximums for its tubeless tires on hookless rims: 5 bar (72 psi) for 25–29 mm, 4.5 bar (65 psi) for 30–34 mm, 4 bar (58 psi) for 35–39 mm, 3.5 bar for 40–44 mm and 3 bar for 45–54 mm. Continental prints the hookless maximum on the tire’s packaging and says never to exceed it. Tick the hookless box and the calculator caps at **5 bar (72.5 psi)**, or at Schwalbe’s lower figure for wider tires. If your tire’s own hookless figure is lower still, enter it as the tire maximum.

## Cold mornings and hot days

Air pressure follows temperature. Continental gives a rule of thumb of about **0.17 bar (2.5 psi) for every 10 °C (18 °F)** of change. Pump to 84 psi in a 20 °C hallway, ride out at 2 °C, and the tire is about 4.5 psi softer than you think. That is why the card has the optional “pumped at / riding at” boxes. On a frosty December commute, check the pressure outside or top up a little indoors, staying under the maximum. On a hot summer day the opposite happens, so never pump to the maximum in the cold.

## Fine-tune by feel

1. Set the calculated front and rear pressure with a gauge you trust, and note which gauge it was: pumps don’t always agree.
2. Ride a familiar loop with some rough patches. If the bike skips sideways over bumps or the ride buzzes through your hands, let a little air out.
3. If the tire feels vague when cornering, squirms, or (with tubes) you feel the rim touch on a sharp edge, add air.
4. Change one wheel at a time by a couple of psi, and write down what you liked. Bicycle Quarterly’s own advice is short: when in doubt, let out some air.

Want a first-order discount code without the newsletters?

Bike shops and tire brands often offer a discount code for an email address. A [free temporary inbox from CleanTempMail](https://cleantempmail.com/) (no sign-up, emptied automatically after three days) receives the code without the newsletters that follow. Place the order itself with your real address, because you need the receipt, delivery updates and any warranty claim.

## Common mistakes

- **Using your body weight alone.** The bike, bottles, bags and a winter jacket count too.
- **Same pressure front and rear.** With a 40/60 split the front needs noticeably less.
- **Pumping to the sidewall maximum.** It’s a safety limit, not a target. Bicycle Quarterly found that maximum-pressure habits under-inflate narrow tires and over-inflate wide ones.
- **Forgetting the rim.** A hookless rim, or a rim with its own maximum, can be the real limit.
- **Trusting the label width.** A “28” can measure 26 to 30 mm depending on the rim. If yours measures wider, enter the measured width.

Heavier load for a tour? Check your [chain wear](https://rapidrambler.me/bike-chain-length-calculator/) and [gearing](https://rapidrambler.me/) before you go. If your ride includes a hike-a-bike section, [Summit Cabin](https://summitcabin.top/) estimates the walking time.

## Tire pressure FAQ

**What psi should a 700x28 tire be?**

It depends on the weight on each wheel. By Frank Berto’s 15% tire-drop chart, an 85 kg rider and bike on a road bike (40/60 split) starts at about 54 psi front and 84 psi rear; at 100 kg all up, about 65 and 99 psi. Never go above the tire’s printed maximum.

**What is the 15% tire drop rule?**

It sets the pressure so the tire’s height shrinks by 15% under the rider’s weight. Bicycle Quarterly found that roughly matches the point where higher pressure stops making the bike faster, so it is a good balance of speed, comfort and grip on average roads.

**Should the front tire have lower pressure than the rear?**

Usually, yes. The bikes Bicycle Quarterly measured carried 35 to 45% of the weight on the front wheel, so for the same tire drop the front needs less air. Weigh each wheel with you on the bike to find your own split.

**What pressure should gravel tires be?**

Michelin’s gravel table starts a 71–80 kg rider at 3.4 bar (49 psi) on 33–35 mm tires, 3.0 bar (43.5 psi) on 40 mm and 2.4 bar (34.8 psi) on 47 mm. Rough or loose surfaces call for a little less, and tubeless lets you go lower without pinch flats.

**How much pressure do bike tires lose in cold weather?**

About 2.5 psi (0.17 bar) for every 10 °C (18 °F) the air cools, by Continental’s rule of thumb. A tire pumped indoors at 20 °C and ridden at 0 °C is about 5 psi softer.

**What is the maximum pressure for a hookless rim?**

It depends on the tire. Schwalbe lists 5 bar (72 psi) for 25–29 mm tubeless tires on hookless rims, 4.5 bar for 30–34 mm and 4 bar for 35–39 mm, and Continental prints its figure on the packaging. Use the lowest of the tire, rim and hookless limits.

## Sources

1. Jan Heine, “Optimizing Your Tire Pressure for Your Weight”, Bicycle Quarterly, with Frank Berto’s chart of inflation for 15% tire drop for 20–37 mm tires and measured weight distributions; reprint hosted by Rene Herse Cycles. The calculator’s line values were read from the chart’s vector drawing in this PDF. [https://www.renehersecycles.com/wp-content/uploads/2015/03/BQTireDrop.pdf](https://www.renehersecycles.com/wp-content/uploads/2015/03/BQTireDrop.pdf)
2. Jan Heine, “Tire Pressure Take-Home”, Rene Herse Cycles, 9 March 2016: limits of the 15% figure, supple tires and lower pressures on gravel. [https://www.renehersecycles.com/tire-pressure-take-home/](https://www.renehersecycles.com/tire-pressure-take-home/)
3. Michelin, “The Michelin tire pressure guide for your bicycle”, michelinman.com (updated 24 July 2026): the gravel and cyclocross table, and notes on rough terrain and tubeless. [https://www.michelinman.com/bicycle/bicycle-tips-and-advice/bike-tire-pressure-guide/the-michelin-bike-tire-pressure-guide](https://www.michelinman.com/bicycle/bicycle-tips-and-advice/bike-tire-pressure-guide/the-michelin-bike-tire-pressure-guide)
4. Schwalbe Tires North America, “Hookless Rims”: ETRTO straight-side (TSS) rims, maximum pressures for Schwalbe tubeless tires on hookless rims by width, and the rule that the lower of the rim and tire maximum applies. [https://www.schwalbetires.com/technology-faq/hookless-rims/](https://www.schwalbetires.com/technology-faq/hookless-rims/)
5. Continental, “Hookless vs. Hooked Rims”: never exceed the maximum pressures, and about 0.17 bar (2.5 psi) more pressure for every 10 °C (18 °F) rise in temperature. [https://www.continental-tires.com/tire-knowledge/hookless-vs-hooked-rims/](https://www.continental-tires.com/tire-knowledge/hookless-vs-hooked-rims/)

Figures checked on 5 November 2026. A starting point, not a guarantee: tire construction, rim width and road surface all move the best pressure, and the maximum printed on your tire or rim always wins.