Technical facts – Off the road tire repair

Options for Repair “C” Clamps vs. Vulcanizers

Options for Repair “C” Clamps vs. Vulcanizers

There are various methods of Section Repair used in the marketplace. These machines are commonly referred to as “C” Clamps. These units often use chemical patches after the plug has been cured, giving rise to possibly the following problems especially on off-the-road tires:

Assuming that the “C” clamp operator is using a chemical patch, after the plug has been cured, there are the following problems with off the road repair using this method:

  1. The chemical patch is precured in a given shape which may or may not fit to the inside radii of the tire. Accordingly, the patch may not fit perfectly to the contour of the tire and air pockets can be created between the patch and the inner liner.
  2. The chemical materials result in a tack or bond wherever the patch touches the inner liner first, again creating air pockets and the impossibility of clearing them out from between the patch and the inner liner.
  3. The patch then cures by the chemical acceleration, the way it has been applied to the inside of the tire, i.e., there is no flow of the rubber into the air cavities.
  4. Assuming it is a tubeless off the road tire, there is no pressure being applied to the patch during the curing process, with the result that as the patch was inserted this is how it will remain.
  5. Failure of the patch then is likely to occur as the tire is flexing in operation, the air pockets expand until finally there is migration and a leak between the patch and the inside of the tire, which can potentially result in under-inflation of the tire and overloading with eventual failure of the repair.
  6. The plug area, cured with a “C” clamp and presuming that pressure and heat are applied from both inside and outside of the tire, will normally cure properly. However, any available size “C” clamp may not cover the full area of the injury that requires repair and likewise it may not conform to the contours of the tire inside and out, causing further problems.
  7. Most “C” clamps usually are unable to supply the high force required for a good compression cure.