Motorcycle Tire Repair: Blowouts

It can happen to you (if it already hasn't)

by David L. Hough

If you've already had a tire failure, you know how a bike can wiggle around and threaten to dump you on the pavement. If you've never had a blowout at speed, consider yourself fortunate, but not yet fully educated. Let's think about controlling a bike with a flat tire. Then we'll ramble through some tire repair techniques, and consider what we can do to avoid tire failures.

Photo: Without a center stand this bike was set on a conveniently located stump and lashed to a tree with a backpack by way of the rear view mirror to stabilize the motorcycle during a rear tire repair. Tire repairs often call for clever thinking on the fly.

Back in the good old days, "blowout" meant a tire carcass that suddenly disintegrated into pieces—and I've had it happen to me. Today's tires are so tough that it's rare to have a blowout, but it can happen if a piece of road shrapnel slices through a tire sidewall, or a heat-damaged tire self-destructs. Tire failures are often a result of a tire that has been losing pressure for a number of miles—even weeks--and eventually gets soft enough to allow the tire to self destruct.

Obviously, it is air pressure inside the tire that supports the bike off the pavement. But let's also note that the pressurized air holds the tire bead against the rim. So, a deflated tire can get dislodged from the rim before the rider can get the bike stopped.

Remember, a two-wheeler requires front wheel steering just to maintain balance. If you can't control steering, it's extremely difficult to keep the bike upright. A front tire deflation makes steering unpredictable, and that makes the bike difficult to balance. A rear tire deflation causes side-to-side weaving that can be very unnerving, but you can still steer the front wheel to maintain balance.

Photo: Today's tires are very durable, but they still need a little TLC to reduce the risks of blowouts. Most importantly, keep your tires inflated to appropriate pressures. The tire in this photo appears to be well inflated when in fact it only has 12 pounds of pressure - about 1/3 the recommended pressure by the manufacturer. Proper tire inflation plays an important role in avoiding blowouts, especially on a tubeless rim such as this one.

If it's a flat, you'll get a vague wandering feeling, as if the road surface were rutted. If the problem is at the front, there will be an increased resistance to steering, and the bike will be more difficult to balance. If it's a rear tire, the rear end will tend to waggle from side to side, requiring you to make increasingly more aggressive steering input to keep it pointed in the direction you want to go.

If you do feel something strange, it's smart to check it out immediately. Even if the tire is losing pressure quickly, you probably have a few seconds to get the bike over to the side of the road. If you continue riding at speed until a soft tire self-destructs, you'll have a lot more trouble getting the bike stopped without dropping it.

Ease off the throttle and get the bike pointed toward the shoulder of the road. Don't snap the throttle closed or attempt to brake hard, since braking force can cause a low tire to slip around on the rim. It's best to squeeze the clutch, roll off the gas, and coast over toward the side of the road.

With a deflated front tire the bike will not respond as quickly to countersteering, but it will respond. If you can, relax your sudden death grip on the bars and let the bike wander a bit—so long as it heads for the shoulder. And, since we tend to subconsciously steer a vehicle toward where we are looking, pick a location on the shoulder that's free of obstructions, and focus on it.

If a tire carcass fails suddenly, the bike will instantly become unstable. But when you do have a "blowout" some day, you may be somewhat amazed that the bike seems reasonably controllable at highway speed. You might even think, "hey, this isn't as bad as I thought it would be." But as the bike slows below about 40 mph, the centrifugal force of the tire dissipates, and it can't hold it's round shape any longer.

So, stay focused on getting the bike headed toward the shoulder, and be prepared for the wobblies to get worse as you decelerate to slower speeds. If a tire really has lost all its pressure, the bike will be darting from side to side between about 30mph and 20mph, and it will be every bit as scary as you've heard it would be. A flat rear tire can actually dislodge from the rim as it squirms around.

The first part of a "blowout" is just keeping the bike under control and getting it off the road without dropping it. The second part is just as important: get the bike away from traffic while you work on the problem. During those last few feet of getting the bike stopped, get it away from the traffic lane. Once the bike has come to a stop it will be difficult to move. It's not uncommon for gawking drivers to smash into vehicles parked on the shoulder. (Remember that bit about a vehicle going where the operator is looking.)

If you need to ease the bike farther away from the traffic lane, (or preferably off onto a side road) you can use engine power. Don't abuse the tire any more than you have to, but it's more important to get the bike well away from the traffic lane than to try saving a tire that may already be beyond repair. The lesson here is that a damaged tire is just an inconvenience compared to being hit by a curious driver, or blown over by the wind blast from a passing truck.

If the tire isn't too badly damaged you may be able to fix it. If it went flat gradually, it's probably a puncture that can be patched. How you patch a tire depends on whether it's tube-type or tubeless. Many current bikes have tubeless tires that can be plugged from the outside. A few machines have spoked wheels that require the use of innertubes. A "blowout" on a tube-type tire is usually a tear in the innertube rather than a tire failure, which means you need to replace the tube.

The quickie approach just to get you to help is to squirt some sticky "inflato-goo" such as ThreeBond Seal 'N' Air inside the tube or tire through the inflation valve. The goo seals the leak and the propellant gradually inflates the tire to a modest pressure. The inflato-goo should be considered an emergency solution, since it makes any future repairs problematic. However, I have resorted to the puffo stuff after running out of other options. (Test bike, Sunday afternoon, bike shops closed, no plug kit on board, no centerstand, ferry to catch—you know the situation).

If it's just an innertube puncture, it's generally acceptable to repair it with a patch, either a rubber patch, or one of those high-tech self-adhesive "Skabs" favored by dirt bikers. When applying a rubber patch, it's important to rough up the surface of the innertube and coat it with rubber cement to help the patch bond to the tube. There are no guarantees, but a properly patched tube should be reasonably reliable for several hundred miles.

Of course, patching a tube means dismounting and remounting the tire, and that requires both tools and a bit of skill. It's very easy to pinch a tube, tear the tire bead, or scratch the rim while you're first learning to use tire irons. It's not that difficult to fix a flat once you've dismounted and remounted a tire a few times to gain some experience. It will also teach you what tools you need to add to your kit.

If you normally ride a machine with tube-type tires, my suggestion is to do some practice dismounting and mounting, using an old "throwaway" wheel and tire at first. After you gain some experience, you don't have to remove the tire entirely from the rim, just lever off enough of the bead on one side to extract the punctured area of the innertube. Experienced Trials riders can patch a tube this way in a matter of seconds without even removing the wheel from the bike!

Tubeless tires can be plugged to get you to the nearest bike shop, but in general you should plan on replacing the damaged tire as soon as possible. The usual method of temporarily repairing a tubeless motorcycle tire is to insert a rubber plug through the hole, using a special tool. Some plug kits contain a sticky string material that is jammed into the hole with a tool. The string stuff is typically what you'll find at gas stations and auto parts stores.

The weapon of choice for many long distance riders is the "Stop & Go Pocket Tire Plugger" kit, which has a reamer for opening up the hole, and a hollow tool for inserting a mushroom shaped plug into the tire. The head of the plug expands inside the tire, preventing it from working out.

BMW tubeless repair kits include a donut-shaped plug that's lubricated with rubber cement and pushed through the hole with a steel hook. The shank of the insertion tool has rough teeth to help ream out the hole. The kit includes CO2 cartridges and a short plastic connector to reach the valve stem.

But the truth is, if the tire is steel belted, it's a real bugger to get the plug inserted through the mesh of tough steel wires. Nor can you depend on a soft rubber plug lasting very long. The belt wires can nip off the plug within a few miles. Just be aware of the limitations of plugs—don't be surprised if you have to plug the same hole several times to get you back to civilization.

Automobile tires are commonly repaired with an internal patch that is bonded to the inside of the tire over the puncture. That's reasonably safe for an automobile, but motorcycle shops are justifiably nervous about patching a motorcycle tire the same way. Stop & Go does make a "permanent" plug that installs from inside the tire like the auto patches, but that requires breaking the bead to get inside. Frankly, if you can limp in to a motorcycle shop on a plugged tire without any further disaster, best advice is to bite the bullet and replace the tire with a new one.

One little suggestion: if you see a big nail imbedded in the tread of your tubeless tire, You'll want to get out your pliers and yank it out immediately. But leave the nail in place until you're ready to plug the tire. That little hole can be awfully hard to find after you pull out the offending nail, and the nail will help slow the leak. Do the exact opposite with a tube-type tire. Pull the nail immediately, but mark the spot on the tire. A nail left in a deflated tire can make a whole row of new punctures in the innertube just by rolling the bike forward a few feet.

It should go without saying, but we'll say it anyway: if the puncture is in the sidewall of the tire, there is no way to repair it safely, whether tube-type or tubeless. You'll need to get a new tire.

Once the hole is plugged, the tire needs to be reinflated. One approach is to use CO2 cartridges, which are connected to the valve stem via a short plastic tube. However, the reality is that it takes several cartridges to inflate a tire, and once you've expended them, that's it. Older BMW "airheads" came with a hand pump secured under the saddle, but it's really awkward trying to hold the pump in position while working the handle, and those of us who have done it can verify that it takes a whole lot of strong-arm pumping to inflate a tire to even 30 psi.

The most practical approach is to carry an electrically powered pump such as the Cycle Pump, Sparrow, or Air Man. The downside of these tiny electric pumps is the very slow air flow. It may require 5 to 10 minutes of pumping to inflate a large rear tire, but when you need air, you've got it handy. And if the plug spits out, you can replug the tire and pump it back up to keep going. More than a few riders use their electric pumps to keep their tires up to desired pressure, rather than stopping at a gas station.

On those adventurous backroads like the Alcan highway, fuel stations generally cater to truckers. And those giant air chucks suitable for reaching the inside duals on a truck are just too big to get between the spokes or behind the brake rotor on many motorcycles. In such situations, you can use a right angle adapter to connect the station chuck to your valve stem. With a pump-in-a-bag like the Cycle Pump, you can easily stuff in a pencil-type pressure gage and a right angle adapter. You only attach the adapter for filling the tire, then remove it for riding.

Photos: The combination of the Cycle Pump and EZ Air gauge allow a rider to get air into the tire easily with an accurate reading anywhere along the ride. There's no need to find the next gas station. At $100 for the pump it's not cheap, but the durability of the metal box outdoes it's nearest competitor.

One real limitation of the small electric air pumps is that they generally can't pressurize the tire fast enough to push the bead against the rim. So, if you need to get a tubeless tire reseated on the rim, you'll need an air source with a much greater flow rate.

One simpler-but-sneakier approach to popping a bead is the Best Rest "Donor Hose". It's just a length of air hose with chucks on both ends, about long enough to reach from your motorcycle tire to another tire. A Donor Hose will pop a reluctant tubeless tire onto the rim and fill a motorcycle tire within a matter of seconds. We can understand how tempting it might be to sneak over to some truck tire while the driver is having coffee. But we suggest you ask permission, not just borrow a little air while the driver isn't looking. Don't say we didn't warn you. A less risky approach is to use another motorcycle tire to pop the bead, then pump them both up.

For those occasions when you need to let air out of a tube or tire, it's necessary to have a tool to remove the valve core from the stem. You could carry a valve tool that has both a core remover and a tap to clean up damaged stem threads. But the most practical technique is to install metal valve caps with core remover ends—available at auto parts stores.

The good news is that today's tires are very durable, and actual blowouts of the carcass are very rare, unless you've done something naughty to your tires. Let's note that a tire carcass is a flexible composite of organic rubber compounds, fabric cords, steel bead wires, and often extra steel belts in the tread area. The tire is made rigid enough to handle side loads (such as steering input), but flexible enough to absorb small pavement irregularities.

To do it's job, a tire needs to be inflated to the correct air pressure. If the pressure is too high, the tire will be too stiff, the ride will be harsh, the contact patch will be reduced in size, traction will be reduced, and wear at the center of the tread will be accelerated. If the pressure is too low, the tire will flex excessively, steering will be "mushy", the shoulders of the tread will wear prematurely, and the rim can be damaged by impacts.

Note that a flexing tire carcass generates heat. A tire that's under-inflated by just 10 psi can cause permanent internal tire damage, especially if the bike is overloaded, or speeds are aggressive. Once the damage has been done, the tire is an accident waiting to happen. It may not fail today or this week, but we shouldn't be surprised if it suddenly comes apart a few thousand miles down the road.

Since the primary way to avoid blowouts is to maintain tire pressures, we need to check our tires before every ride. Motorcycle tires are so rigid that you can't easily spot a low tire just by looking. If a tire looks low, it's probably under 20 psi. You really need to check pressures with a gage. "Pencil" type gages are cheap and reasonably accurate.

The place to start is to look up the pressures the manufacturer lists for the bike in your owners manual, or on a placard on the bike. Note that tire pressures are normally increased for heavier riders, two-up riding, extra loads, or higher speeds.

Recommended pressures are sometimes listed in bar, sometimes in kPa, and sometimes in psi. We'll include a handy pressure conversion chart at the end.

But let's note that the pressures recommended by the bike engineers are for the stock tires that came with the bike. If you change to different tires, then it's time to consult the tire manufacturer. Believe it or not, there are tire specialists eager to discuss your bike with you, and recommend tire pressures for different conditions. So, get their phone numbers, and ring 'em up for a discussion.

Let's also note that tires are "organic". That is, more like apples—less like steel bars. Tires "spoil" within a few years, especially when exposed to sunlight. The outside of the rubber gradually hardens and cracks, while the internal rubber loses elasticity and strength.

Fortunately, tires are dated. So, a clever rider checks the manufacturing date on a tire before buying. Frankly, you shouldn't even think about putting on "new" tires that are older than five years. The date is coded, of course, to make it less obvious that a tire is getting "stale". The date code is the last digits of the "DOT" number, which represent week and year. So, a serial number such as "DOT ATCX 4 1004" would be the 10th week of 2004—the second week of March, 2004. Prior to 2000, the date code was in 3 digits. If any of your bikes have tires with only 3 digits for the date codes, I'd strongly suggest replacing them immediately.

For those of us who have several machines, or don't put down many miles per year, it's important to get the freshest tires available, since those tires may be on the bike for several years, gradually dying of old age rather than being worn out. If you see ozone cracks in the rubber, the tire is history.

Photo: The manufactured date is the last 4 digits on the DOT line, for tires manufactured after 2000.

One other caution with tube-type tires. Install a new innertube with a new tire. Blowouts of tubes can almost always be traced to an aging tube that was re-used in a new tire. As I've discovered for myself, an old innertube may look perfect, but the rubber can be rotten and ready to split a few miles down the road. Trust me on this one: "New tire; new tube."

Photo: This tire is the original that came on a 2003 machine, photographed in January 2006. It's dated "2202" (mid-May, 2002). The tread isn't quite worn out, but note the little cracks between the tread blocks that indicate the rubber has deteriorated to the point of needing replacement.

Good News, Bad News

The good news is that today's tires are so tough that sudden deflations are a rare occurrence that few riders will have to experience. The bad news is that there are lots of sharp thingies lying on the roadways, and there are also a few nasty people around who think it's fun to spike or slash motorcycle tires while you're not looking.

So, this would be a good time to check your tire repair kit and ensure you've got what you need on board to fix a flat. Most importantly, get in the habit of checking your tires before heading out on a ride, so they don't self-destruct.

David Hough is a long-time motorcyclist and journalist. His work has appeared in numerous motorcycle publications, but he is best known for the monthly skills series " Proficient Motorcycling " in Motorcycle Consumer News, which has been honored by special awards from the Motorcycle Safety Foundation. Selected columns were edited into a books " Proficient Motorcycling and More Proficient Motorcycling " published by Bowtie Press. He is also the author of "Driving A Sidecar Outfit." A pocket handbook, " Street Strategies " span style="mso-fareast-font-family: Times New Roman; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA">is also on the market now.