If you work in any field that uses large vehicles with tough tyres, i.e. agriculture, construction, mining, and industrial production, then it's extremely important to make informed decisions when purchasing replacement tyres.

OTR tyre basics

Off The Road (OTR) tyres are designed for use on machines and equipment that largely operate away from highways hence the name.

Key aspect in determination of the correct OTR tyre for your machine is the TRA code (Which takes into account tread thickness/depth, speed and ply rating).

Tyre manufacturers refer to the TRA standards when producing OTR tyres. TRA codes are a major criteria for customers who want to ensure they find the right OTR tyres.

Tread Patterns of OTR Tyres

There are four main OTR tyre patterns that are designed to offer area-specific efficiency in relation to traction and terrain compatibility, and are able to withstand the corresponding specific challenges like cuts, heat, flotation, wear & tear.

Example traction pattern

Traction pattern

OTR tyres with a traction pattern are often directional tyres; meaning that they must be assembled and mounted in the correct direction on the vehicle. The pattern structure of these tyres results in excellent traction. In addition, tyres of this kind have high self-cleansing tread properties, to make sure traction is not lost.

Example rock pattern

Rock pattern

Tyres with this pattern are used in demanding circumstances - often on rocky surfaces where extra protection is needed against damage and cuts. The pattern is made from a rubber compound that is extremely robust. These types of OTR tyres are characterized by S-shaped (zig-zag) pattern rows and grooves, They are located on the left-hand and right-hand side of the tread, meaning against the driving direction for better traction.

Without pattern (slick)

Example pattern-free tyre (slick)

Without pattern (slick)

Pattern-free OTR tyres do not feature grooves or notches, apart from two narrow grooves on the shoulder for tyre wear indication. Such tyres offer maximum resistance against wear and incisions.

Uses of slick tyres

  • On steam rollers in road building,
  • When smoothing and/or flattening surfaces.
  • Also regularly used on loaders in the (underground) mining industry because they offer high resistance against damage and excellent robustness.

Block pattern

Example block pattern

 

Block pattern

Characterized by relatively wide tread depth, and rounded shoulders.

Block pattern OTR tyres have blocks that are equally spaced and positioned in rows, block pattern tyres create a relatively large contact area. If heavy loads must be transported, these tyres keep pressure on the ground relatively low and help to maintain flotation qualities. These tyres are ideal for use on soft, muddy surfaces. We regularly see these tyres mounted on crash tenders in size 24R20.5.

Tread Thickness of OTR Tyres

With reference to TRA codes, there are three general classifications for tread thickness of OTR tyres: regular, deep and extra deep. Deep and extra deep are 1.5 and 2.5 times thicker than regular, respectively. The thicker treads have greater cut and wear resistance.

Although thicker treads give greater wear and cut resistance, they also generate and retain more heat. Accordingly, work conditions for thick tread tyres should be thoroughly evaluated to prevent heat related damages, notably separation. Deep and extra deep tread tyres have almost the same overall diameter which is larger than regular tread tyres. When replacing regular tread tyres with deep or extra deep tread tyres, the larger overall diameters of the thicker tread tyres should be taken into consideration.

Types of OTR tyres

These organisations have defined four types of OTR and industrial tyres - based on their application. The designated category can be found on the sidewall of the tyre. The types are listed below; and are reflected in the first letter(s) of the TRA code:

  • C = Compactor (road-building machines and steam rollers),
  • L = Loader/Dozer,
  • G = Grader,
  • E = Earthmoving (transport; scrapers, articulated and rigid dump trucks),
  • IND = Industrial (port).

The following digit further define the tyres by representing the tread depth: -

  • 2/3 stands for 100% tread depth
  • 4 stands for 150% tread depth
  • 5 stands for 250% tread depth