Bike Tire Pressure Calculator

Use this calculator to find the optimal tire pressure for your road, gravel, mountain, hybrid, or BMX bike.

How to Use This Calculator

1. Select your bike type: road, gravel, mountain, hybrid, or BMX. The calculator fills in a typical setup for that bike, which you can then change.
2. Enter your measured tire width in mm: measure your inflated tire with calipers or a ruler across the widest point. The sidewall number is a starting point, not the actual width.
3. Enter your weight: your body weight plus the bike plus any gear (water bottles, saddle bag, full pockets). Choose kg or lbs.
4. Select your tire casing. Tires with an inner tube get a pinch-flat margin on rough surfaces, and the calculator shows a note for your setup.
5. Choose a riding surface: select the terrain that best matches your ride. Surface selection has the biggest single effect on the result.
6. Set Conditions to Wet if riding in rain, wet mud, or on wet leaves. This reduces pressure by about 9% for more grip.
7. Set Rims to Hookless if your rims are hookless. Pressure is then capped at 72 PSI, since hookless rims are rated to 72.5 PSI (5 bar).
8. Enter your email if you want your results in your inbox. You can leave it empty.
9. Press Calculate my tire pressure. You get front and rear pressures with a fine-tune range of about ±5%. If a result was raised to a floor or capped, a note explains why.

Understanding Bike Types

Bike type sets the weight split between your wheels. The safe pressure range comes from your tire width instead (see below), so a road bike on 35 mm tires or a gravel bike on 50 mm tires gets limits that fit the tire.

Bike Type	Front / Rear Weight Split
Road bike	48% front / 52% rear
Gravel bike	47% front / 53% rear
Mountain bike	46.5% front / 53.5% rear
Hybrid	47% front / 53% rear
BMX	50% front / 50% rear

Road bikes put more weight over the front than mountain bikes because of the more aggressive, forward-leaning position. The further forward the rider sits, the more load the front wheel carries, and the closer the front and rear pressures get.

These splits match the methodology used by professional tire engineers at companies like Silca.

Safe Pressure Range by Tire Width

The calculator keeps every result inside a floor and ceiling based on measured tire width. The floor protects the rim and prevents tubeless burping. The ceiling stops narrow tires being pumped to unsafe pressures. Values between the rows are interpolated.

Tire width	Floor	Ceiling
23 mm	70 PSI	130 PSI
25 mm	60 PSI	120 PSI
28 mm	50 PSI	110 PSI
32 mm	40 PSI	95 PSI
35 mm	35 PSI	85 PSI
40 mm	28 PSI	75 PSI
45 mm	24 PSI	65 PSI
50 mm	20 PSI	55 PSI
55 mm	17 PSI	48 PSI
60 mm	15 PSI	42 PSI
65 mm	13 PSI	36 PSI

If your result hits the floor or ceiling, the calculator marks it and tells you the pressure it originally calculated.

How to Measure Your Tire Width

The tire width you enter should be the actual inflated width in millimeters, not the number printed on the sidewall. A tire labeled 28c can measure anywhere from 26 mm to 31 mm depending on rim width and brand.

How to measure:

1. Inflate the tire to the pressure you normally ride.
2. Place calipers or a ruler across the widest point of the tire (not the rim).
3. Read the measurement in millimeters.

If you don’t have calipers, use the sidewall number as your starting point. Most modern tires measure 1–3 mm wider than their stated size when mounted on a standard rim.

Common tire width examples:

Tire label	Typical actual width
25c road	26–28 mm
28c road	28–30 mm
40 mm gravel	40–43 mm
2.35″ MTB	58–62 mm

Surface Conditions Explained

Surface selection is the biggest single input in the calculation. Rougher and looser surfaces get lower pressure, so the tire can follow the ground instead of bouncing over it. Here is what each option means.

Paved Surfaces

• Smooth road: Fresh tarmac, well-maintained cycle paths, velodrome surfaces. Prioritize rolling efficiency. This gives the highest calculated pressure of any surface type.
• Rough road: Chip-seal, older tarmac with cracks and patching, typical urban roads. A small reduction compared to smooth road keeps the tire compliant over surface imperfections without sacrificing much efficiency.

Gravel Categories (G1–G4)

Gravel comes in four distinct levels. The difference between G1 and G4 is roughly 15–20 PSI for a typical rider. Choosing the wrong category is one of the most common reasons people feel uncomfortable on gravel despite having a “gravel calculator” result.

• G1 (Packed gravel): Compact, well-maintained gravel paths. Similar to a firm dirt road or a well-graded forest track in dry conditions. Minimal pressure reduction compared to rough road. Example: a smooth gravel cycle route or a well-maintained unpaved park road.
• G2 (Typical gravel): Loose, medium-sized stones on a firm base. A standard gravel road or typical gravel race course. The most common gravel scenario. Example: a gravel sportive route, a quiet gravel farm track.
• G3 (Rough gravel): Larger, looser stones with significant surface variation. Unmaintained tracks, washed-out forest roads, agricultural tracks. Requires noticeably lower pressure to maintain traction and control. Example: a remote country lane that hasn’t been graded in years.
• G4 (Rough loose): Very loose, deep, or chunky gravel. Coarse road ballast, rocky double-track, post-storm conditions. Run significantly lower pressure here for grip and to avoid rim strikes. Example: a mountain access road with large loose stones, or a gravel race stage through high-alpine terrain.

Trail Surfaces

• Light trail: Packed dirt, smooth singletrack, dry forest paths. Classic cross-country mountain biking terrain.
• Technical trail: Roots, rocks, tight switchbacks, variable traction. Enduro-style terrain where the trail surface changes constantly.
• Muddy: Wet mud, clay, deep forest after rain. The lowest pressure of any surface type for maximum tire deformation and grip.

Casing Types Explained

Your tire’s casing type doesn’t change the base pressure. What it changes is the pinch-flat margin needed on rough surfaces (rough pavement, G3 and G4 gravel, trails and mud). The calculator adds that margin for you: a share of the pressure, with a minimum in PSI so low mountain bike pressures still get real protection.

Tubeless. No inner tube. The tire seals directly to the rim with liquid sealant. There is no tube to pinch, so no margin is added and you run the calculated pressure. Hard rim strikes can still damage the tire or rim, so stay within the fine-tune range. Tubeless is the recommended setup for gravel and mountain bikes, and increasingly popular for road too.

Clincher, standard casing. A conventional tire with an inner tube, standard rubber or nylon casing. The most common setup worldwide. On rough surfaces the calculator adds about 8%, and at least 3 PSI, to reduce pinch-flat risk. On smooth pavement and G1 to G2 gravel, no margin is added.

Clincher, supple casing. A clincher with a higher thread count (TPI) casing, typically 120 TPI and above (standard casings are around 60 TPI). More supple, better vibration damping. Requires slightly less safety margin than a standard clincher, so the calculator adds about 5%, and at least 2 PSI, on rough surfaces.

Tubular. The tire is glued or taped to a special rim, with the tube sewn inside the casing. Used mainly in road racing and cyclocross. Less prone to pinch flats than a tire with a separate tube, so no margin is added. Tubulars need tubular rims and cannot be used on hookless rims.

What Do Wet Conditions Do?

Enabling Wet conditions lowers the calculated PSI by about 9% on every surface.

Lower pressure means more tire deformation. More deformation means a larger real contact area with the road, which is exactly what you need when traction is reduced by water, mud, or wet leaves.

Example: A road bike setup that calculates 74 PSI rear on dry smooth tarmac gives 67 PSI rear with wet conditions enabled. A gravel setup at 34 PSI dry becomes 31 PSI wet.

This is a consistent modifier. Unlike an additive offset, a proportional modifier applies the same relative reduction regardless of base pressure, so a high-pressure road setup and a low-pressure MTB setup both get approximately the same 9% reduction.

Example Calculations

Example 1: Road Cyclist, Smooth Tarmac

• Rider weight: 75 kg. Bike + gear: 10 kg. System weight: 85 kg.
• Bike: road bike, 28 mm tire
• Surface: smooth road, dry
• Casing: clincher standard

Result: 70 PSI front / 74 PSI rear (4.8 / 5.1 bar)

At 85 kg system weight on smooth tarmac with a 28 mm tire, the front runs about 6% lower than the rear, because it carries less load. A standard clincher on smooth road runs at the calculated pressure with no safety margin.

Example 2: Gravel Rider, Mixed G2 Surface

• Rider weight: 68 kg. Bike + gear: 12 kg. System weight: 80 kg.
• Bike: gravel bike, 40 mm tire
• Surface: G2 typical gravel, dry
• Casing: tubeless

Result: 32 PSI front / 34 PSI rear (2.2 / 2.3 bar)

A 40 mm tubeless tire at these pressures will deform well over a gravel surface, providing good traction and reasonable comfort. Because it is tubeless, run exactly at these values with no safety margin.

Example 3: Mountain Biker, Technical Trail in Wet Conditions

• Rider weight: 80 kg. Bike + gear: 15 kg. System weight: 95 kg.
• Bike: mountain bike, 2.35″ (59 mm) tire
• Surface: technical trail, wet conditions enabled
• Casing: tubeless

Result: 18 PSI front / 20 PSI rear (1.2 / 1.4 bar)

Wide tubeless tires at sub-20 PSI deform dramatically over roots and rocks, improving grip and impact absorption. The wet modifier lowers pressure further from the dry-trail result. At these pressures, check regularly for any signs of rim contact.

Why Front and Rear Pressure Differ

The rear wheel carries more weight on virtually every bike type. The drivetrain, seat tube angle, rider weight distribution, and rear bag loading all increase rear-wheel load compared to the front.

Higher load on the rear wheel requires higher pressure to avoid squirm and rim strikes.

The calculator runs the front about 6% lower than the rear. In practice that means:

• Road bike: about 4–5 PSI
• Gravel bike: about 2–3 PSI
• Mountain bike: about 1–2 PSI

Running equal pressure front and rear is one of the most common setup mistakes. It means the front is overinflated (harsh, reduced traction), or the rear is underinflated (pinch-flat risk, sluggish handling), or both.

PSI vs Bar: Which Unit to Use?

The calculator shows results in both units. Use whichever your pump reads.

Unit	Common use	Conversion
PSI	USA, UK, most road cycling	1 bar = 14.5 PSI
bar	Europe, most off-road / tubeless	1 PSI = 0.069 bar

There is no accuracy difference between the two units. Bar is just the metric equivalent of PSI.

FAQs