A motorcycle tire bead is the inner strip of the tire that is sealed to the wheel’s rim, reinforced by a thin steel or copper strip to prevent air from leaking out of the tire via the slitted opening between the rim and the rubber tire.
The friction between the seal that binds the tire to the wheel is backed by the metal strip embedded in the tire for extra support during rough rides and tire-warping heatwaves.
A tire that fails to bead won’t hold the air required for essential motorcycle operation, but why won’t your motorcycle tires bead?
Here’s Why Your Motorcycle Tires Won’t Bead:
The primary reasons motorcycle tires won’t bead are overinflation or improper PSI, inadequate tire installation, punctures, cracks, warps and rips, dry rot, and road hazards. A tire bead that’s slipped off can be repaired; a bead seal that’s been punctured won’t seal properly again.
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What Does a Motorcycle Tire Bead Do?
A motorcycle tire bead creates the seal from the friction between the bead and the wheel rim, while a steel or copper strip supports the bead in maintaining the seal during severe motorcycle vibrations or tire distortions.
Where Is a Motorcycle Tire Bead Located?
The motorcycle bead rests along the tire’s inner edge, right where the tire meets the wheel. The bead runs along the “inside” of the tire instead of the outside tire tread.
On an installed tire, the bead is easily found along the base of each sidewall, where each sidewall meets the tire.
On an installed tire, the bead should be hidden behind the edge of the wheel unless there’s significant damage to the wheel, tire, or the bead’s seal.
1. Bike Tires Are Over/Under Inflated
If your motorcycle tires are over the PSI levels specified on your tires and in your owner’s manual, your tire can slip its portion enough for its bead’s seal to break. If under-inflated, the tires lack the tension required to maintain the integrity of the tire bread’s seal.
We suggest never inflating your tires past the spec PSI—some riders pre-inflate their tires before riding up to high elevations that cause deflation.
We recommend avoiding this practice and adding air once your tires have actually deflated to ensure you don’t dislodge your tire bead from the wheel.
Once above the suggested PSI, the stiffening sidewalls of the over-inflated tire separate from the wheel. This not only makes for a rough ride, but your tires also wear faster when they’re over-inflated.
Over-pumped tires incur wear and tear at an increased rate, contributing to performance loss, traction decrease, and a greatly slimmed-down contact area between the tire and the road.
On the other hand, if your tires are inflated below the suggested PSI level, the reduced content changes your tire’s shape and tension. Reduced tension can cause the tire to slip enough to damage your motorcycle tire’s bead.
The metal strip embedded in your bead is expected to reinforce the bead during slips caused by the impact shock of rough roads. That said, this function is most efficiently performed when your bike’s tires are inflated at the spec PSI.
2. Motorcycle Tires Are Below Spec PSI
This is the opposite problem from above, and I’d say the most common cause of a damaged bead seal on a motorcycle.
If your bike’s tires are under-inflated, the lack of tension can cause the seal to slip from the wheel’s rim enough to cause permanent damage.
While the reinforced seal of the bead will activate during a slip with the proper amount of PSI in the tire, if the tire is less inflated than advised, the slip’s distance might be too drastic for the reinforcement to matter.
3. Improper Tire Installation
Whether you slapped the new tread on yourself or had it done professionally, a tire installed incorrectly can slip off due to vibrations or get knocked around by road debris.
In some cases, the bead’s seal won’t seal in the first place. A few miles down the road, you’ll find yourself wobbling to the side of the road, realizing in the breakdown lane that your tires deflated themselves through the broken seal of the bead.
An improper tire installation can stop the tire bead from adequately sealing, whether the mechanic used the wrong tools or failed to sufficiently clean the tire’s beads and surfaces and prep the site with proper lubrication.
This is another one of the more common causes of bead failures on a motorcycle on this list. The upside is that motorcycle tire beads are generally built to endure once the tire is mounted correctly.
If you’re unsure of your general motorcycle wheel and tire installation knowledge, it might be good to take the bike to a well-reviewed seasoned pro, ensuring they use the proper tools, sizes, kits, etc.
To make sure you know what questions to ask at your next tire installation or, for our mechanically savvy readers, what to look for at your next DIY session, let’s start with reviewing the basics:
How Does a Motorcycle Tire Bead?
A motorcycle tire beads by sealing to the motorcycle’s wheel, creating friction between the bead and the wheel rim.
The friction is maintained and reinforced by a strip of steel embedded in the tire.
Where is the Bead on a Motorcycle Tire?
The bead is located on the inner edge of the motorcycle tire, where the tire meets the wheel.
Once installed, the bead can be recognized as the seal found along the internal base of each of the sidewalls, where the tire and wheel rims meet.
4. Punctures, Debris, and Road Hazards
Anything that can damage a tire or wheel rim can damage the bead, including sharp metal objects, shattered glass, splintered wood, potholes, curbs, and even torn-up concrete can all put a puncture in your tire severe enough to protrude the bead and stop it from sealing.
Jagged metal, spikes of broken wood, potholed concrete, glass shards, and curbs are some of the most common hazards that can prevent your motorcycle’s tire from beading by tearing, puncturing, or ripping through the bead’s seal.
Even a rugged thumbtack or misplaced nail can break the seal, sometimes slipping and falling undetected.
It might be as simple as a nail or tack that slipped in, punctured the bead seal, and slipped out unnoticed.
In some cases, riders miss the fact that the bead is failing. They get puncture kits slapped on the tire’s wound and refill them with air only to discover slow leak symptoms they can’t track down.
This can happen in a few different ways:
- It could have been a matter of the bead itself being punctured.
- Maybe the force of the impact dislodged the bead enough to prevent the seal from closing.
- Perhaps while the punctured tire was deflated, the underinflation caused a slip, as mentioned in the section above.
- Either way, once your tire bead fails, patching the puncture in the tire wall or tread won’t be enough to stop a slow leak from airing you out.
5. Ripped Or Torn Tire
It’s pretty widespread moto-knowledge that a ripped tire isn’t a safe bet on a motorcycle; make sure you inspect the bead for rips and tears just and thoroughly as you examine the sidewalls and tread.
If the motorcycle tire is ripped, lack of tension, incorrect positioning, or airflow in and out could prevent the bead from sealing to the air-tight position required for safe motorcycle riding.
The tear might be too small to notice; as soon as you notice a slow leak on a bike, it’s imperative to track it down. A slow leak causes chronic deflation, which, as covered above, can cause slips and dislodges that make the leak even worse.
If your bike’s tire doesn’t seal to the wheel, it could be because a slow leak in the tire reduces the PSI enough to affect your motorcycle’s bead.
6. Old Age Or Dry-Rot; Reduced Elasticity
If the motorcycle in question was a backyard ornament for extended periods, dry rot could be why your motorcycle tire won’t bead.
Dry rotted tires incur a significant decrease in flexibility, a quality that permeates the tire bead’s ability to seal itself to the bike’s rim.
A dry-rotted tire could also be cracked in a perfect place along the seal to allow air to break through, rendering the bead useless.
In short, if your tires are old and you think you have an air leak, but you haven’t been able to track it down, and if you know for a fact you don’t have a leaking valve stem or a crack in the tire itself, the leaking bead is likely the cause.
This may be because of old age, dry rot, reduced elasticity, etc., but any motorcycle tire with a bead that won’t seal because of a leak shouldn’t be ridden.
A slow leaking bead can lead pretty quickly to a complete blowout, as a deflated tire gets much hotter, much faster.
7. Bent, Damaged, Or Corroded Wheel Rim
If the motorcycle’s wheel rim is corroded, rusted, or busted along the length where the tire beads meet the wheel, the bead will fail, and your tire will lose its air content.
Corrosion is more commonplace on magnesium alloy and die-cast aluminum bike rims. Still, you or your moto-mechanic should inspect the rims of any motorcycle wheel before installing and sealing a new tire and its beads.
Otherwise, your motorcycle tires could fail to bead.
Even the most celebrated and expensive motorcycle wheel on the market can’t seal to a thoroughly corroded rim. As we’ve mentioned a few times, a motorcycle with a leaking tire is unsafe to ride.
In some cases, the wheel is so corroded that air can leak through the corrosion even if the bead does seal.
A similar situation happens when using improper wheel weights results in damage. A bad casting job can cause the rim to leak, but that’s a subject for another article.
The important thing here is that whether your motorcycle tire won’t bead or the rim is leaking, avoid injecting the tire with sealant, or you’ll only be making a mess you have to clean out to replace the tire and/or rim.
Can You Fix a Motorcycle Tire That Won’t Bead?
In some cases, if the tire and rim are both in good condition and the problem was simply that the bead got knocked loose, you can reseat the tire bead and, as a result, reseal it.
If the bike tire’s bead has incurred any damage at all, whether a tiny bend or a large puncture, the whole tire needs to be replaced.
Whether it’s the tire’s internal chords, rubber seals, or whether the beading area of the tire is shredded from the road or rim, a damaged bead can’t be resealed.
When in doubt, we suggest consulting a specialist, as leaking tires are dangerous enough on a four-wheeled vehicle.
On a motorcycle, a blowout could cause injuries or worse.