How to mount a tire on a rim: lube, bead, seating pressure

In short. Take the tyre off fully deflated, with the valve core removed. Put it back on with a tyre lubricant on both beads and the rim's bead seats, never silicone, mineral oil, solvent or anything flammable, and seat the beads by inflating against a ceiling: 40 psi (2.75 bar) in the US and Canada and in the French tyre makers' procedure, 3.3 bar then 4.0 bar under the German standard. If the beads have not seated at the ceiling, let the air out, lubricate again and start over; more air can break the bead wire. Fit a new valve, keep tools 20 cm from a pressure sensor, balance the wheel, and torque the nuts to the car maker's figure.

Why a tyre can go on at all

A tyre bead holds a hoop of steel wire that does not stretch. The rim is wider at its flanges than in its middle, where a well (or drop centre) runs all the way round. The bead only gets over the flange because the part of the bead opposite the tool sits down in that well, which gives the slack you need. That one fact explains most of what goes wrong: if the opposite side of the bead is not in the well, no lever and no machine will pull it over without damage.

Three more words matter. The bead seat is the band of rim the bead sits on and seals against. The hump is a small ridge inboard of the bead seat that keeps the bead in place when pressure drops; Continental says rims for tubeless radial tyres must have humps or ledges. Seating the bead means pushing it over the hump onto the seat with air, which is why a seating pressure exists.

Taking the old tyre off

The French tyre makers' body, the TNPF, publishes a machine procedure for car tyres (TNPF, in French, our translation). In short:

1. Deflate completely: remove the cap and the valve core and wait. The TNPF says never to break the bead of a tyre that is not fully deflated; OSHA's rule for truck rims says the same: "Tires shall be completely deflated by removal of the valve core before demounting" (29 CFR 1910.177(g)(1)).
2. Remove the balance weights, clip-on or stick-on.
3. Break the beads with the bead breaker at least about 20 cm from the valve, so you do not crush a pressure sensor, and just above the rim edge: higher up the sidewall, the TNPF warns, it can break the carcass and leave bulges when the tyre is reinflated.
4. Clamp the wheel from the outside, with plastic protectors on the jaws.
5. Set the head with the valve at 12 o'clock and a gap of 2 to 3 mm to the rim flange.
6. Lift each bead over the head with the lever, checking that the opposite part of the bead is in the well.

There is no "bead-breaking pressure": it is zero. The force comes from the tool. EUWA, the association of European wheel makers, gives the reason in its recommendations: on some wheel types, unseen damage can make the assembly explode during removal if the tyre still holds air. It also says a tyre and wheel that have run flat or at 80 per cent or less of the recommended pressure should be removed and inspected (EUWA ES 1.09, 2.2).

Bead lube: what to use and where

The lubricant lets the bead slide over the flange and the hump without tearing, and helps it centre on its seat. Washing-up liquid and other household products appear in none of the texts we read, so we cannot tell you they are safe for a given tyre. Use the tyre maker's product.

Mounting the tyre: step by step

1. New valve. "Always use new valves" when replacing tubeless tyres, writes Continental; the TNPF says the same and adds that a rigid metal valve is tightened with a torque wrench.
2. Inspect the rim: cracks, cracks in the spokes or disc, oval bolt holes (TNPF). EUWA says not to use damaged parts and not to try to repair them.
3. Clean the bead seats. The TNPF uses a soft bronze-bristle brush on steel and alloy rims; EUWA wants the bead seat areas free from rust and rubber deposits so the tyre seals.
4. Check the tyre and the match. No cuts, no exposed cords, no run-flat damage (TNPF). Continental is blunt about size: the tyre and rim must match in diameter, a 17-inch tyre does not go on a 17.5-inch rim, and a tyre mounted on the wrong rim must be scrapped because it may have been overstretched. Width matters too: see rim width for a tyre size, and compare sizes with the tyre size calculator. Onyx Forged does not recommend a size or an offset: the car maker's documents set them.
5. Lubricate beads, flanges, humps and seats.
6. Place the valve at least 20 cm from the mounting head and check the rotation or "outside" marking on the sidewall (TNPF). Directional and asymmetric tyres are explained in our tyre rotation guide.
7. Fit the first bead, then the second, pressing the part already fitted down into the well. EUWA describes the hand version for a single-piece rim: start on the narrow bead seat side, push the lower bead over the flange and into the well, hold the upper bead with one lever and work round "by short steps" with a second. For low-profile tyres the TNPF uses a bead clamp or the machine's bead pusher.
8. Inflate to seat the beads, without the valve core for enough airflow, up to the ceiling below and no further.
9. Once both beads are seated, the TNPF goes to 3.0 bar, refits the core, then sets the car maker's pressure for that wheel position.

Bead seating pressure: a ceiling, not a target

The beads move onto their seats as pressure rises. Every text that gives a figure gives a maximum; OSHA adds that a machine-mounted tyre should get only the minimum pressure needed to force the bead onto the rim ledge. The HSE also asks you to check whether the rim has a maximum pressure stamped on it. Psi values in brackets are our conversion (1 psi = 6.894757 kPa, NIST SP 811).

The figures do not contradict each other: they come from different standards and do not all name the same stage. The TNPF links its 40 psi to the "Safety Warning" marking required in the USA and moulded on some sidewalls: read the sidewall before inflating. We did not find a published Australian figure; there, follow the warning on the tyre and the tyre maker's instructions.

If the beads are not seated at the ceiling, the TNPF says to deflate, relubricate fully and try again, and to consult the tyre maker if it still fails. Its warning is plain: ignoring the limit can break the bead wire and cause an accident. Continental's is that the tyre can burst, with serious or fatal injury.

Why a few psi matter. Here is our own arithmetic for one example tyre, a 225/45 R17, chosen only for the sum. Its outer diameter is 431.8 + 2 × 101.25 = 634.3 mm, so one sidewall is a ring of π/4 × (0.6343² − 0.4318²) = 0.170 m². At 275 kPa (40 psi) the air pushes on that ring with 46.6 kN, about 4.75 tonnes-force; at 400 kPa, 67.8 kN. The HSE makes the same point for a typical commercial vehicle tyre: around 2/3 m² of sidewall at 517 kPa carries over 34 tonnes, and a failure can release it "at an angle of up to 45 degrees from the rupture" (HSE HSG261, paragraph 139).

Staying safe while you inflate

• Hold the wheel. Continental says the rim must always be secured on the machine while the tyre is inflated; without a restraint, inflate in a safety cage. EUWA asks for a cage of suitable strength "or at least" safety chains to complete inflation.
• Never inflate a loose tyre lying on the floor (Continental).
• Stay out of the trajectory. The HSE asks for an airline hose long enough to stand outside the likely explosion path, and no unrestricted airlines or valve connectors you have to hold in place. EUWA: "Never stand in front of the wheel."
• Eye and ear protection and work shoes (Continental).
• Measure: EUWA says always use an air gauge.
• Know the valve's limit. A rubber snap-in valve typically takes 4.5 bar (65 psi) at most, according to Continental; above that a metal or high-pressure valve is needed.

By hand, at home, without a machine?

This is what most searches ask, and the texts we read answer it in one direction. Continental opens its own instructions by saying that following them is not enough to mount or remove a tyre: leave it to qualified tyre fitters.

• US. OSHA's rule on rim wheels says: "It does not apply to the servicing of rim wheels used on automobiles," nor pickups and vans on car or LT tyres (1910.177(a)(1); standard dated 1974, last amended December 2011). Its procedure is still the best public summary of the risks, and it asks workshops to inflate truck tyres only in a restraining device, behind a barrier or bolted on the vehicle, to the minimum pressure needed to seat the bead, with no flat, solid surface within one foot of the sidewall.
• UK. The HSE says tyre repair and replacement "should therefore only be tackled by competent staff", and that low-profile and run-flat tyres are a challenge "even to experienced employees" (HSG261, paragraph 135, first edition 2009).
• Europe. EUWA: mounting a tyre onto a rim "must be carried out by trained personnel only" (ES 1.09, 2.4). In Germany, the road safety council DVR asked on 28 October 2020 for a compulsory competence card for tyre fitters. It notes that damage from poor mounting of UHP and run-flat tyres usually sits in the bead area, cannot be seen from outside, and can later make the tyre fail.
• Canada and Australia. The 40 psi ceiling cited by Continental covers the US and Canada. We could not read a public provincial or state work-safety page on car tyre fitting for either country while writing, so we give no rule for them.

What none of these texts describes: seating a bead with a ratchet strap round the tread, or with a flammable spray lit inside the tyre. Continental and EUWA forbid the second outright.

None of the texts we read forbids a private owner from mounting a tyre, but a home job lacks three things the texts ask for: a way to hold the wheel or a cage while inflating, a regulated airline with a gauge long enough to keep you out of the blast path, and a balancer. Changing a wheel is a different job: handbrake on, chock the wheels that stay on the ground, and if anyone needs to reach under the car, raise it and set it on axle stands, never on the jack alone (HSE HSG261, paragraphs 136 to 138); then see wheel nut torque.

TPMS sensors and the valve

Two distances protect a valve-mounted pressure sensor: the bead breaker at least about 20 cm from the valve, and the valve at least 20 cm from the mounting head when fitting (TNPF). Continental asks for new valves on every tubeless tyre change; for a sensor, the sensor maker's instructions say which parts to renew. Valve types and when to renew them are in tyre valve stems. If the warning light comes on after a tyre change, read TPMS light flashing or solid.

Run-flat, low-profile and finished alloy wheels

Run-flat beads are stiffer, and Continental allows its SSR run-flat tyres to be fitted only by specially trained and accredited specialist dealers; more on how they work in run-flat tyres.

On alloy and forged wheels the risk is to the wheel as well. EUWA asks workshops to avoid impacts and high forces, which can reduce the wheel's fatigue life and cause vibration, and to avoid scratches to the surface protection, which open the way to corrosion (EUWA ES 1.07, 2.3 and 2.4). Some wheel makers go further: one forged wheel maker's installation instructions ask for the bead seat to be "generously lubricated", tyres mounted with contact-free tyre mounting machines and stick-on weights only, because clip-on weights can damage the wheel (installation instructions). Your own wheel maker's instructions come first. On a polished, diamond-cut or painted wheel, ask the shop which machine and which jaws it will use before you leave the wheels.

After mounting: balance, pressure, torque

The old weights came off with the tyre, so the new assembly has its own imbalance and needs balancing; see wheel balancing. Set the cold pressure on the car maker's placard, not the seating figure. On the car, EUWA asks for clean contact faces, the vehicle maker's torque with a torque wrench, tightened progressively and crosswise, and a check after about 50 to 100 km "always after a wheel or tyre replacement" (ES 1.07, 3.5 to 3.7). If a tyre would not seat or a bead looks uneven, have it checked before you drive.

Frequently asked questions

How do you seat a tyre bead?

Lubricate both beads and the rim's bead seats, remove the valve core for airflow, hold the wheel on the machine or in a cage, and inflate while standing out of the trajectory. Stop at the ceiling: 40 psi in the US and Canada and in the TNPF procedure, 3.3 bar over the hump under the German wdk standard.

What PSI do you need to seat a bead?

No text we read gives a minimum, only ceilings: 40 psi (2.75 bar) in the US and Canada and in the French tyre makers' procedure, 3.3 then 4.0 bar under the German standard, 3.0 bar in Japan. If the beads have not seated at 40 psi (2.75 bar), the TNPF says to deflate, relubricate and start again, not to add pressure.

What can I use as tyre bead lubricant?

A tyre mounting paste or lubricant recommended by the tyre maker (Continental), a neutral non-aggressive paste (EUWA), a nonflammable rubber lubricant (OSHA). Never silicone, mineral oil, solvent or anything flammable.

Can you mount a tyre by hand without a machine?

Physically, yes, with levers and the well of the rim, as EUWA describes for single-piece rims. But the UK HSE and EUWA reserve the job to trained staff, and a home set-up usually lacks a cage or restraint, a regulated airline and a balancer. Low-profile and run-flat tyres are a shop job.

Does OSHA's 40 psi rule apply to car tyres?

OSHA 1910.177 excludes rim wheels used on automobiles, and its text gives no 40 psi figure: it refers to the manufacturer's maximum. The 40 psi limit for the US and Canada comes from the tyre industry (RMA, now USTMA), as cited by Continental and the TNPF.

Why won't my tyre bead seat?

Common causes in the texts we read: not enough lubricant, a rusty or rubber-coated bead seat (EUWA), a tyre stored flat and deformed (HSE), or a tyre that does not match the rim. Clean, relubricate and retry; if it still fails, ask the tyre maker. A bead seat that is pitted or corroded is covered in tyre bead leaks on corroded rims.

Do I need a new valve when I change a tyre?

Yes for tubeless tyres, according to Continental and the TNPF. For a TPMS sensor, renew the parts the sensor maker lists.

Do I need to balance after mounting a tyre?

Yes. The weights come off when the tyre is removed, and the new tyre and rim have their own imbalance.

Wheels for your next set of tyres

Onyx Forged makes made-to-order forged wheels designed to JWL/VIA standards; the customiser shows the options, and the tyre fitting stays with your tyre shop.

Sources

• OSHA, 29 CFR 1910.177, Servicing multi-piece and single piece rim wheels, paragraphs (a)(1), (b) and (g).
• HSE, HSG261, Health and safety in motor vehicle repair and associated industries, paragraphs 135 to 142 and Table 2.
• Continental, tyre mounting safety instructions (in German; our translation).
• TNPF, tyre removal and fitting procedure for light vehicles (in French; our translation).
• EUWA, ES 1.09, Safety and service recommendations for wheels, sections 2.2 and 2.4; EUWA, ES 1.07 (June 2020), sections 2 and 3.
• DVR, Sachkundenachweis für die Reifenmontage, 28 October 2020 (in German; our translation).
• HRE Wheels, warranty and return policy, section on initial installation (a wheel maker's instructions, cited as a source).
• NIST Special Publication 811, Appendix B.9, conversion factors.

All pages were read on 16 October 2026.

The Onyx Forged design office.