How to Mount a Tire on a Rim by Hand: Drop Center, Lube and Bead Seating

What this guide covers

“Mounting a tire” here means putting a tire onto a bare one-piece rim, not bolting a wheel to the car. It is the second half of a tire change; the first half is under how to remove a tire from a rim.

The machine side follows the owner's manual of the Harbor Freight Pittsburgh manual tire changer, item 58731, which we read according to the copy of the owner's manual on ManualsLib and paraphrase. Rim preparation, lubrication and inflation follow the bulletins of the U.S. Tire Manufacturers Association. Your own machine's manual and the instructions of the tire, wheel and vehicle makers come first. We have not run these steps in a shop.

Why the drop center decides everything

The bead of a tire is built around a hoop of steel wire. It is stiff, and it is smaller than the rim flange it has to cross. It gets over only because the rim has a deep channel in the middle, the drop center or well. When one side of the bead sits down in that channel, the opposite side gains just enough slack to pass the flange.

The tire makers put it in one line: make sure the tire beads are completely in the drop well of the rim during the mounting process. They also name the three main causes of bead damage and seating trouble: installing the tire over the flanges improperly, poor lubrication, and beads that are not centered on the rim. Every step below works against one of the three.

Eight steps

1. Clean and inspect the rim, fit a new valve

   Corroded or dirty rims should be cleaned thoroughly so that the bead seat area is clean, including the valve hole. Bent or cracked rims should be destroyed and replaced. Used snap-in valves are always replaced when tires are replaced; on wheels with pressure sensors the tire makers recommend replacing the parts of the sensor's valve kit and following the vehicle maker's service requirements.

2. Check the tire and its orientation

   The tire diameter has to match the rim diameter. The changer's manual says to place the tire on the rim in the correct orientation. Look at both sidewalls for rotation arrows and inside or outside markings before you go on, and check that nothing is lying inside the tire.

3. Secure the wheel

   On a floor-post changer, set the rim on the base so that the lug pin goes through a lug hole into the slot below, add washer and slider, thread on the post cap and tighten it with the flat end of the bar. With tire irons, support the rim so that it cannot slide.

4. Lubricate both beads and the rim

   The manual has bead oil applied to the upper and the lower bead. The tire makers are more exact: both tire beads and the rim must be lubricated, and on the rim that means the humps, the bead seating surfaces and the tops of the flanges, plus the sides of the drop well. Use a lubricant made for the job; see tire mounting lube.

5. Push the lower bead on

   Lay the tire on the rim and push down on opposite sides to start the lower bead. Then put the flat end of the bar through the tire, hold the tire down with your free hand and work the rest of the lower bead over the upper edge of the rim. The motorcycle bulletin notes that the lower bead can often simply be pushed on.

6. Lever the upper bead on in small steps

   Turn the bar so that its hook side faces the rim and press down so the hook tucks the bead under the rim edge. Slide the bar along the center post for leverage and work around the rim. Keep the part of the bead that is already on pushed down into the drop center the whole time. The manual warns against hitting the side of the tire with the bar to force it on. With irons, the motorcycle bulletin has the valve area go on last and rules out pry bars, sharp lifting and substitute tools such as screwdrivers.

7. Center the tire and seat the beads

   Before inflation, rotate and center the tire on the rim. Restrain the wheel, stand back and stay within the limit in the box below: never more than 40 psi to seat beads.

8. Set the pressure, check for leaks, balance

   Inspect both sides of the tire to be sure the beads are evenly seated. Then set the operating pressure from the vehicle's tire placard, never above the maximum molded on the sidewall. The changer's manual ends with checking for leaks and having the tire balanced by a qualified automotive technician.

Lubricant: where, which and how much

Lubrication is the step with the most detail in the tire makers' bulletins, and the one most often cut short.

• Where. On the tire, from the rim-aligning ring down to the bead toe, on both beads. On the rim, the humps, the bead seats and the tops of the flanges. The stated purpose is that the bead moves smoothly over the flange and seats completely against it.
• Which. A commercially available bead lubricant, used as its maker says. Silicone, petroleum and solvent-based lubricants must not be used; the full list is on the lube page linked above.
• How much. Enough to cover those surfaces, and no more: the bulletin asks for care to avoid excess lubricant, to keep moisture out of the air chamber.
• How thin. A mixture that is diluted too far dries too fast and acts as if no lubricant had been used. One that is not diluted enough stays wet and may let the tire rotate on the rim, which the bulletin names as a cause of balance and uniformity problems.

A third hand for the upper bead

The hard part of mounting alone is that you need one hand on the bar and one holding the mounted section down in the well. Bead clamps do the holding. The AFEISOL nylon bead clamps^* (paid link) are listed by their seller as a drop center tool, two in a pack: they sit on the rim edge and keep the bead from climbing back onto its seat while you work around. We know them from the listing only, so check it against your wheels. A clamp replaces neither lubricant nor patience.

Seating is its own step

The changer's manual says only to inflate the tire to the proper pressure and not to over-inflate; it names no seating pressure and no restraint. Treating a floor-post changer as a machine without a positive lock-down device is our own cautious reading, not a statement from that manual. The full procedure and its sources are on the page how to seat a tire bead; cages and restraints are explained under tire mounting safety.

Typical mistakes

• Big bites with the bar. Work around the rim in small steps. A long reach loads the bead against the flange instead of sliding it over.
• Letting the far side climb out. If the bar suddenly needs much more force, the mounted section has left the drop center. Stop and push it back.
• Lubricating the bead only. The rim surfaces need it too.
• Hammering. The manual rules out hitting the side of the tire with the bar and gives the risk of serious injury as the reason. What bead damage looks like and when a tire is no longer fit to mount is covered under tire bead damage.

Where to go from here

The machine procedure from the first step to the last is under how to use a manual tire changer, and the whole job including balancing is laid out in how to change tires at home. If you do not own a changer yet, the models are in the comparison of manual tire changers; the overview of all tools is on the manual tire changer homepage.