from Goss’ Garage by Pat Goss
Don’t you hate that your mind is always being dominated by thoughts of all the stresses on your tires as you drive? Yeah right; if that’s true you’re probably either a tire engineer or one very strange person. Actually, most drivers are completely oblivious to their tires until they have a problem. I guess their theory is as long as tires turn they’re okay. But when their neglect causes premature wear, a flat or heaven forbid, a blowout, all hell breaks lose! How could this happen? If you consider tires simply as round, black, rubber donuts you might be interested to know that today’s tires are actually highly engineered assemblies made up of hundreds of components and compounds.
Not only are tires amazing examples of modern technology, they are your sole connection with the road and require better care than most of you give them. A monthly pressure check should be considered as important as gas in the tank because all tires lose pressure. This is normal and is caused by air molecules passing through pores in the tire’s rubber. Because pressure loss is normal, continuous and unpreventable a good tire gauge is a must-have tool. But the best tire gauge in the world is as worthless as a box of rocks unless it leaves your glove box and connects with your valve stems.
Although slow pressure loss is normal loss from a puncture isn’t. Roads are littered with everything from ladders to sofas to pieces of cars and space junk just looking for a tire to puncture. Fortunately most punctures can be safely repaired. But safe repair or a tragedy in waiting depends on where the puncture is on the tire and how it’s repaired.
Sidewall punctures; large holes and cuts are all usually non-repairable and require a new tire. Many other conditions aren’t safe to repair either but yes or no can only be determined with a careful examination of the damage and the tire in general. For a repair to be safe the damage must be small and located between the two outermost ribs of the tire’s tread. Any damage beyond the flat surface of the tire’s tread means a new tire, not a repair.
Here’s something that might change your car or tire buying habits; high-performance, speed-rated, run-flat and specialty tires are usually deemed non-repairable. Consider all repairs to specialty tires as strictly temporary and remember once repaired speed-rated tires lose their speed rating, so drive accordingly.
Even if the puncture is repairable the repair probably won’t be done right. Although primitive and out of date the most common way to fix a tire is still to force a plug through the hole from the outside of the tire and call it fixed. A plug is quick and cheap but usually not totally safe. Tragically, dangerous repair procedures are far too common because many of you choose saving a few bucks over safety.
A proper puncture repair involves removing the tire from the wheel and checking the tire for internal damage. Omit removal and you wouldn’t know about internal damage until the tire failed. After passing the internal inspection a special plug-patch is installed from the inside of the tire. As its name suggests this is both a plug and a patch. A plug-patch plugs the hole through the tread and patches the inside of the tire. A second acceptable repair involves a rope-type plug installed from the outside combined with sealant applied to the inside of the plug with the tire removed from the rim.
Proper procedures seal the outside and the inside of the puncture and sealing both is critical. Failing to seal the inside can allow air to leak into the body of the tire causing separation between the layers of rubber and belts. Failure to seal the outside allows water to enter and corrode the steel belts under the tread. Either can cause catastrophic failure! Having safe tires depends on you so closely monitor pressure and never ask for or permit anything except a proper repair.
© Copyright 10/26/2009 Pat Goss. All Rights Reserved.