Filling the Void - Tire Review Magazine

Filling the Void

Filling the Void

Performing section repairs on agricultural tires – bias or radial ®“ is relatively simple. But because it’s a lengthy and painstaking process, there are many opportunities for error.
Ag tires, which include farm tractor and implement tires, logger and skidder units, and high flotation utility tires, are required to carry heavy loads while dispersing that weight over a large footprint, and maintain a high degree of traction on variable surfaces – often soft, wet and full of potential punctures.
There are four basic parts to any section repair: preparing the injury, filling the injury, curing the fill material and applying the repair unit. The same process is used whether the injury is in the tread area, the shoulder, or the sidewall.
First, the tire must be inspected carefully and completely, inside and out, and the tire technician must locate and mark all injuries and remove any foreign objects that remain in the tire.
Next, the technician must determine if the tire is, in fact, repairable. Based on industry standards, an ag tire cannot be repaired and should be scrapped if the injury falls within the non-repairable area of a tire, the tire shows signs of being run flat, there is any ply separation present that is beyond repairable limits, any bead damage is beyond repairable limits, weather checking or cracking has exposed some body cords, and/or other section repairs have been made in the same area of the tire.
If the injury can be repaired, the first step is to thoroughly clean out the jury, removing all loose or damaged material. A knife or cap cutter can be used to remove large portions of damaged rubber and trim back any damaged steel cables.
A carbide cutter should be used to trim back any damaged steel cables. On sidewall injuries, use a skiving knife to trim back body plies. All exposed fabric or steel cords must be trimmed back into solid rubber to assure a reliable bond and help prevent future moisture damage.
The interior of any skived out area should be buffed to a dull velvety texture using a low speed (2500 rpm maximum) buffer.
The injury should be prepared in the shape of a “Y,” with the outside area of the injury skived to about a 45Þ to 60 angle (to the centerline of the injury), tapering into a channel through to the innerliner side of the tire. The outside edges should be rounded slightly, and the outer surface of the injury area should be buffed about one-inch wider than the cavity to allow for overflow of fill material.

Select Right Repair Unit

Measure the injury at the widest point of the opening in the body plies. With that measurement and the tire’s ply rating, use the repair supplier’s reference chart to select the appropriate repair unit (patch) for either a radial or bias ply tire.
Depending on what type of spot vulcanizer and repair process you’re using, apply the appropriate cement or vulcanizing solution. Make sure the entire injury is clean and free of loose debris before applying any cement or bonding solution. In general, make sure to thoroughly coat the entire injury area, inside and out, and extend the cement/-solution coating about 1/2-inch beyond the buffed area. Let the cement/solution dry about 15 minutes or until it’s slightly tacky.
The next step is to fill the injury with uncured rubber. You can either use strip stock and an extruder gun, or you can hand fill the injury with cushion gum. Either way, it is vital that the injury be completely filled, flush to the edge of the innerliner and about 1/4-inch above the exterior surface of the tire.
Then tightly stitch down the fill material, working from the center out to remove any trapped air in the fill rubber.

Finishing the Repair

Unless the tire under repaired is being retreaded at the time of repair, the fill material must be cured using an electric spot vulcanizer, with the repair unit being installed using a cold chemical vulcanizing cement. Because there are so many different spot vulcanizers on the market, we cannot go into details. However, it is important to carefully follow the spot vulcanizer manufacturer’s instructions.
Once the fill material is cured and cooled, make sure to carefully buff the exterior of the cured rubber flush with the rest of the tire. This not only helps improve the appearance of the repair, it helps prevent any pulling or ripping of the repair while the tire is in service.
Using an appropriate cleaning solution, go back and clean and scrape the innerliner. While the repair unit is still wrapped in its protective coating, place it over the injury, making sure to center it over the injury area and align it properly in relation to the beads according to the repair manufacturer’s instructions.
Using a marking crayon, outline the repair unit on the innerliner, making the outline about 1/2-inch wider than the repair unit. This establishes your buffing area. Make sure to mark index lines on both the repair unit and the innerliner – at all four sides ®“ extending at least 1.5 inches out on the innerliner. This will make it easier to replace the repair unit back over the injured area.
Using a low speed buffer, completely buff the area inside the repair unit outline to a dull, velvety texture. After buffing, make sure to use a brass bristle brush to clean the buffed area, and use a repair vacuum or other vacuum to clear away any buffing debris.
Install the repair unit using the repair unit manufacturer’s instructions. In general, most repair units are installed by first applying a thin coat of chemical vulcanizing solution, allowing it to dry about 5 to 10 minutes until it’s slightly tacky to the touch.
Be careful to not under- or over-cement the repair area. Over-cementing can lengthen drying time and could cause adhesion problems, while under-cementing will prevent a solid bond between the tire and the repair unit. Do not use blow dryers, fans, heat lamps or any artificial heat sources to speed drying times. This will only dry the outside surface of the cement, leaving damp cement below the flashed surface.
When the vulcanizing solution is dry, peel the protective backing from the repair unit back about one-inch from either side of the center. Be sure not to touch the exposed portion of the repair unit. With the tire in a relaxed state and using the index marks, apply the unit.
Firmly press down on the center of the repair unit, then slowly remove the remaining protective backing, pressing down firmly as each portion of the unit is exposed. Once in place, use a hand stitcher to stitch the repair unit in place, working from the center out.

Seal The Area

After the repair unit is completely stitched in place, finish the repair by applying a repair sealant. Make sure to coat all edges of the repair unit, cover all overbuff areas on the innerliner, and extend coverage at least 1/2-inch beyond any buffed area.
As you can see, section repairs to agricultural tires is relatively easy. The important thing is to properly clean and prepare the injured area, and closely follow all repair manufacturer’s instructions. If you don’t prepare the injury to accept the fill material and repair unit, the repair will likely fail. 

You May Also Like

Training and Technology Will Lead the Way in OTR Tires

When we look at how OTR tires keep up with innovations in equipment, it’s all about maximizing productivity.


After two years of probably the strangest logistics we've lived through—and a roller coaster ride of an economy—the OTR tire market is surprisingly robust. The construction industry has slowed down slightly, and there's a lot of talk about a recession, but so far, we haven't seen a lot of publicly or privately funded projects pull back, and quarries and mines are running hard. All that activity is good for the tire industry.

Maxam Tire Completes Core Size Range for Agrixtra H Series

Maxam Tire completed the core size range for four-wheel drive self-propelled nutrient applicators. The company says these sizes to the Agrixtra H will further allow farmers’ and growers’ access to its product line. Related Articles – Yokohama OHT Releases New Size for Alliance Agri Star II – Winter Tire Market Flat, But EV-Specific Products Bring

Yokohama OHT Releases New Size for Alliance Agri Star II

Yokohama Off-Highway Tires America (YOHTA) has released the new 800/70R38 size of its popular Alliance Agri Star II farm radial tire. The new, larger size features a 173D high-load rating and is rated for speeds of up to 40 mph. Related Articles – Last-Mile Delivery Tires Set to Outpace Long-Haul Tire Volumes – Yokohama Releases

Alliance-agri Star II
BKT Highlights Ridemax Radial Floatation Tire for AG, Tank Trucks and Spreaders

Modern farming implies the use of heavy implements such as spreaders, or tank trucks, and other trailers to do their job in the fields and to travel from one plot of land to another. Different tasks, different conditions, different needs. This a dilemma for many farmers when it comes to choosing the right tire to

Maxam Tire Adds New Sizes to its Ag Tires Family

Starting this fall, the all-new Agrictra 70 and 65 sizes will be available for purchase and will be offered as a part of the Maxam North American Spring Savings Program for 2023 from Maxam Tire. Related Articles – Yokohama Off-Highway Introduces New Skid Steer Radial Tire – Maxam Tire Adds the MS700 to its Industrial

Other Posts

Goodyear Adds Wrangler HT Tire to Light Truck Lineup

The Goodyear Tire & Rubber Company has added the Goodyear Wrangler Workhorse HT to its Wrangler light truck tire lineup. Goodyear says its Wrangler Workhorse HT provides all-season traction, a confident ride and the strength to go the extra mile. Related Articles – Comparing Trends in All-Season and All-Weather Tire Segments – Continental Debuts Enthusiast-Driven

Comparing Trends in All-Season and All-Weather Tire Segments

When it comes to all-season and all-weather tires, consumer expectations have been a driving force in both segments, affecting everything from OE fitments and sales trends to tire performance. Essentially, consumers want the convenience of not having to swap tires every winter, as well as the safety and performance provided by capable all-weather tires, according

All season all weather vredestein hypertrac
Continental Debuts Enthusiast-Driven ExtremeContact Sport 02

From timed autocross laps to drifting on a skid pad and mastering knee-jerk braking and turns on a raceway, dealers, influencers and members of the media were treated to a crash course in performance racing while testing out Continental’s newest UHP summer tire, the ExtremeContact Sport 02. Related Articles – BKT Launches EM 933 Super

BKT Tires Launches Agrimaxfactor Tire For Tractors

BKT has launched the Agrimaxfactor, a new tire series for tractors for transport and soil tillage operations. Related Articles – Hercules Launches TIS TT1 Max Traction Mud-Terrain Tire – Atturo Tire Enters the Powersports Market with Two New Tires – Global Tire Manufacturer Ralson Enters US TBR Market The company says it developed the series