For seasoned technicians, mounting and sealing tires may seem like old hat. After all, when you’ve done a thousand tires, you’ve pretty much got the hang of it, right?
Yet myths and misperceptions persist about how to do the job properly.
Some bad practices have developed too. Remember the days when a common way to seal a tire was using lighter fluid and an open flame? Using an explosion to seal a tire may have been dramatic but it was never safe!
Our industry has become much more sophisticated and the most obvious bad practices may be behind us. But even with today’s super-helpful tire equipment, there’s still room for error – especially if you’re new to the job!
Whether it concerns bead breaking, tire removal, rim inspection, or the use of sealers, differences abound. And then there’s TPMS to worry about. This relatively new and particularly sensitive technology complicates the wheel removal and installation process a little bit.
Given the breadth of the topic, we thought it would be worth looking at the prescribed way to seal and mount a tire. Thanks to Jas Singh at Fountain Tire Marine Drive in Vancouver for demonstrating.
Breaking the bead
When breaking the bead of a tire, best practice is to remove the Schrader valve completely from the tire valve. Make sure the tire is completely void of air pressure before pressing the bead breaker shoe against the tire. Position the TPMS sensor directly across from the bead breaking shoe so as not to damage the TPMS sensor.
Removing the tire
Rotate the tire until the TPMS sensor is in the 11 o’clock position before removing the tire. This will have the tire moving over the TPMS sensor and reduce the chance of accidentally damaging of the sensor.
Cleaning the rim or wheel
Corrosion from salt, moisture, and road grime can cause pitting on the sealing surface of the wheel, creating slow leaks that can be hard to find. Many times, this is repairable by cleaning the bead surface or using a professional wheel repair service. If you’re working with chrome wheels, be aware that the chrome may have separated from the wheel. If that’s the case, the wheel is not serviceable and should be replaced. Use a wire wheel or wire brush to remove obvious corrosion and surface grime. Then clean the wheel seating bead on both top and bottom. Use a cleaner to remove any dust or residual particles. Apply the sealing agents as per the manufacturer’s instruction. The sealer can fill in the minor imperfection left by the corrosion
When installing a tire with TPMS sensors, move that sensor to the 5 o’clock position then rotate the turntable to install the tire. This helps the tire clear the TPMS sensor during installation.
Pressurizing the tire
When inflating a tire, again, make sure the Schrader Valve has been removed from the tire valve. This allows a greater volume of air to enter the tire and enables the tire to seat on the rim. Never exceed the manufacturer’s maximum inflation pressure embossed on the tire. A bead blaster is available for those stubborn tires that don’t want to seat properly.
It all sounds simple enough, right? Like I said, tire mounting is not rocket science, but it does need to be done correctly. After all, your reputation – not to mention the safety of your customers – is on the line.
Tire Repairs made easy
This make-shift repair job on a sidewall of a Mustang GT broke the rules in many different ways. It was actually holding air when it was brought into Desboro Garage in Desboro, Ont., but the service advisor there managed to sell a replacement to the vehicle owner.
Tire repairs are a common procedure at many shops. They’re a customer pleaser too, because a quick repair means they don’t have to buy a new tire that will cost hundreds of dollars.
While it’s nice to be the hero, sometimes you have to tell them their flat tire is ready for the scrap bin. Puncture repairs are only possible in the tread area of the tire. Where damage extends into the shoulder of the tire or sidewall, that tire cannot be repaired.
For speed rated tires, you need to find out from the manufacturer whether it can be repaired and whether it retains its speed rating after the repair. Similarly, some run-flat tires can be repaired, while others cannot. You need to check with the manufacturer.
Even if the type of tire is repairable, the extent of damage will tell you whether you should go ahead.
For example, you shouldn’t even start the job on a tire with less than 2/32” left on the tread. Neither can you repair a tire that is leaking from the spot of a previous repair. If the puncture is more than a quarter inch inch (6mm) in diameter, it cannot be repaired.
Where repair is possible, use a two-piece stem and patch repair, or a one-piece stem and patch kit. Never use just a plug, or just a patch. A plug by itself is only a temporary repair. A patch alone doesn’t fill in the missing rubber that the puncture created. The hole will allow water and air to enter the cords, which could result in a blister. Plugs and patches are meant to work hand-in-hand.
In case it needs to be said, patches go on the inside of the tire! Tyler VanGaalen, a technician at Competition Toyota in London, Ont. sent in this EyeSpy picture of a patch job that had been done to the outside of the tire. Needless to say, it was never going to last!
Repair work must only be done when the tire is fully removed from the hub. You can’t complete a proper inspection when it’s still attached to the wheel assembly. Work in good light as you check the external and internal surfaces for damage and debris.
Remove any debris and ream the puncture channel, starting from the inside, a minimum of three times using an electric or air-powered drill. Repeat from the outside and then use a probe to check for splits in the radial plies.
Buffing the area thoroughly and evenly with a low-speed buffer. Be careful when buffing the inner liner. If you expose the casing body cords, the tire must be scrapped.
After you apply cement, allow it to dry naturally. Don’t used forced air, fans, or heaters to accelerate the drying time.
When you’ve applied the patch and plug, re-inspect the entire tire carefully. After remounting and inflating the tire, check again for damage or leaking.
Thomas Hines, RSE, ASE-MCAT, has held a wide variety of jobs in the automotive aftermarket. He currently lives in Vancouver, B.C.