Bike tire pressure calculator.

Worked example

A 170 lb rider on a 30 lb bike is 200 lb in total. Frank Berto’s chart gives 136 psi for a 19 mm tire, 126 for 20 mm, 106 for 23 mm, 88 for 25 mm, 76 psi for 28 mm, 60 for 32 mm and 46 for 37 mm. For a 28 mm tire this tool shows 76 psi (5.2 bar), 68 psi at the front and 84 psi at the rear. Berto’s own article uses 45% of the weight on the front wheel and 55% on the rear, which is why he suggests about 10% less in front and 10% more behind.

How it works

Berto measured 50 tires at pressures from 40 to 160 psi under loads from 20 to 220 lb, and drew the pressure that gives a tire drop of about 15% of the tire’s section width for each load. The seven 200 lb values above are the numbers in his article. The slope of each line (how much pressure rises per extra pound) was read off the published chart by TNAADO, so results away from 200 lb are approximate, within about 5 psi. They reproduce the Bicycle Quarterly reprint example (100 kg rider and bike on 20 mm tires: 125 psi front, 155 psi rear) to within 3 psi.

What to keep in mind

Berto drew the chart in the 1990s for narrower tires. Bicycle Quarterly’s Jan Heine notes the 15% target was based on tire maker recommendations rather than testing, and that on rough roads and gravel lower pressures can be faster. Berto himself says he does not think the 15% criterion is valid for mountain bike tires. Treat the result as a starting point and adjust to the road, the tire and your rim.

Sources

Retrieved 2026-10-16. The 200 lb pressures, the 15% criterion and the 10% front/rear adjustment are from Berto’s article; the pressure-per-pound slopes are read from his published chart image by TNAADO and are approximate.

• Frank Berto, All About Tire Inflation (15% tire drop, chart, 200 lb values, front/rear)
• Jan Heine, Bicycle Quarterly, Tire Pressure Take-Home (origin of the 15% target, lower pressures)
• Bicycle Quarterly, Myths Debunked: front and rear tires should run at roughly the same pressure

FAQ

What tire pressure should I use for my weight?

It depends on your total weight and the tire width. For 200 lb of rider and bike, Frank Berto’s chart gives 106 psi on 23 mm, 88 psi on 25 mm and 76 psi on 28 mm road tires. Enter your own weight and width above.

Should front and rear tire pressure differ?

Berto suggests about 10% less in front and 10% more behind for a typical 45/55 weight split. Bicycle Quarterly has argued that front and rear can run about the same pressure, so it is a judgement call.

What is the 15% tire drop rule?

Berto found that a tire that sags about 15% of its section width under load balances rolling resistance, comfort and puncture resistance, and drew his pressure chart for that drop.

Does this work for mountain bike or gravel tires?

No. Berto says he does not think the 15% criterion is valid for mountain bike tires, and the chart stops at 37 mm road tires. Follow the tire maker’s guidance for wider and off-road tires.

Is it safe to go above the sidewall maximum?

No. Never exceed the maximum pressure printed on the tire or rim. If the chart gives more than the sidewall allows, choose a wider tire.