Course: Tyre management | Last Updates: 9th October 2015
It is paramount that the two front wheels are parallel or have a slight toe-out. This will help prevent irregular shoulder wear and maximise efficiency. This is covered in the first academy in this series.
Pressures and Loads
Ensuring tyres run at the correct pressure is one of the easiest maintenance tasks you can carry out and it will have wide ranging benefits. It will ensure even tyre wear, prevent cracking, provide protection against impact and assist long life.
In terms of overall performance, it will maximise fuel usage, minimise compaction and ensure a comfortable ride for the driver. All these factors will have an impact on cost. Regular pressure checks and adjustments for field and road work will help you get the most from your tyres, but it is critical when you have just had a new tyre or rim fitted, a new valve or a puncture repaired.
Valves are cheap, but the consequences of deflation are not, so always fit a new one when you change tyres or rims. Do not exceed the maximum load or speed ratings and aim for the correct power to weight distribution. For standard 4WD work, tractor gearing should be set up to distribute power 35:65 front to rear and weight at 40:60.
Ensure that the tyre is the correct size for the rim. Even a slight mismatch can result in poor traction, irregular wear, sidewall cracking, bead damage or rim slip. In extreme cases complete loss of fitment can occur once the wheel is put under load, such as heavy cultivation work, for example. Flange roll-over is a visible sign that the tyre is too large for the rim or has been incorrectly fitted. Bead damage or chafing indicates the presence of rim slip.
Regularly check rims for signs of cracking, corrosion or damage. Pressure loss may well be gradual, but it will become a persistent problem if left unchecked. Ensure all wheel nuts are in place and tight. It is also a good idea to keep them lightly greased in case the wheel needs to be removed. A shorn stud is a big inconvenience and a lost wheel can be catastrophic.
Although it is tempting to squeeze every last penny from your tyres, badly worn rubber is a false economy. Not only can they be illegal and prone to blowouts, but they can end up costing you more in lost performance, particularly traction and handling. Rubber is perishable and can degrade, so you should consider replacing tyres that are over five years old, even if they have tread remaining.
Think carefully before considering used tyres. Modern tyres are a complex series of components and layers and although the tread may seem sound, you will not know the condition of the structure and carcass and whether it has been subject to abuse or damage. Never mix bias and radial tyres on the same axle or different tread patterns. Radial tyres have a longer tread life than bias-ply tyres.
What to look out for
Following the above advice will minimise the likelihood of problems, but it is good practice to look out for damage and to get it checked by a tyre professional. If caught early enough, some damage can be repaired. Left unchecked, costly problems will occur. A puncture in the field is an inconvenience, but a blowout at speed on the road can be life threatening.
Look for cracks, cuts, missing chunks and bulges. There should be no canvas, wires or other material visible. Sidewalls are often the most vulnerable parts of the tyre because they are exposed and do the most flexing. Particular care should be taken when near kerbs, entering narrow gate openings or in tight turning circles with machinery or trailers attached to the rear.
Other indications of tyre problems – besides the visual ones – can be observed in terms of performance. Slow punctures should be treated as soon as possible. Road hop, skipping, rapid or irregular wear are all signs of a problem.
Essential tyre checklist
- check the track width to ensure the wheels are parallel.
- Radial run-out – the tyre being “out-of-round” – normally a manufacturing fault.
- Pressure checks are one of the easiest tasks you can carry out and will have wide ranging consequences.
- Tread base creasing/cracking – damage where the lug meets the tyre surface, usually caused by overloading/under inflation and very high torque loading of the lugs, on hard surfaces, eg roads.
- De-lamination – where a thin layer of rubber peels back slightly from the tread area. Looks unsightly, but is normally only a cosmetic.
- Bead damage – where the tyre meets the rim. Often caused by poor fitting or mismatched tyres/rims.
Always remember to check any measurements and pressures with your machinery dealer and tyre manfucturer.
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