Frequently Asked Questions
Why is the farm tyre industry changing from a familiar size marking like 208R38 to metric marking like 520/85R38?
Auto and truck tyres converted to metric size marking to provide standardization in the tyre industry worldwide. The farm tyre industry is using the same format. The most significant advantage of this change to a new size standard is that the new load and inflation standards applied to metric sizes were set based on more modern material properties.
Why are codes like R-1, R-1W, F-2, I-1, and HF-2 used with agricultural tyres?
The soils in which agricultural tyres must operate vary greatly due to composition and moisture content. To perform well in these soils, different tread patterns are used. For traction in dryer, well drained soils, a shallow tread with many lug edges to bite into the soil work best. These designs are labeled as R-1. In wetter soils, a deeper, more widely spaced lug is best, and these are designated R-1W (W for wet). The 'F' group is for front farm tyres and the 'I' group is for implements. The 'HF' group is for high flotation. Further details on these application codes and descriptions are available from the various tyre industry suppliers and standards groups.
What is the meaning of 'Ply Rating' and 'Load Index'?
Ply Rating is a measure of the strength of bias tyres. The higher the rating number (always an even number), the greater the inflation that a tyre can hold. From that inflation pressure, a load carrying capacity is known from published load/inflation tables. Load Index is a number that represents what load a tyre can carry. A higher number implies a higher load capacity. Once again, the load number must be looked up in a table or read from the tyre stamping.
Front lead is often mentioned regarding MFWD tractors, what is this?
Tractors that have power driven front and rear axles where the front drive tyres are smaller than the rear tyres are called MFWD (Mechanical Front Wheel Drive) tractors. Another term often used is Mechanical Front Assist (MFA). Regardless of the term, the tractor needs the front tyre to lead the rear. That is, the front must have a slightly faster ground speed than the rear to maintain proper pull and tension in the drive gearing. A lead of 1 to 4 percent is common, and slippage on the soil keeps the tractor running smoothly.
For adding ballast to a tractor, which is best, liquid or cast weights?
In general, we recommend using cast weights. It is important for overall performance that a tractor has the recommended total weight per horsepower. The weight should also be split between front and rear axles in accordance with the tractor manufacturer's recommendations. The use of cast weights allows the weight to be adjusted more easily as the tractor work requirements change from task to task. Although more costly initially, the ease of use with cast weights will prove to be beneficial overall.
When must I use dual drive tyres?
Use of dual tyres is usually done to carry a higher load than a single tyre is capable of carrying. One other consideration is the power of the tractor. For any given field speed and tractor power, there is a level of torque that the tyre must transmit to the ground. As speed is reduced, the torque level goes up. Any given size and rating of a tyre has a limit to the amount of torque it can transmit to the ground. Use of dual tyres is an effective way to handle higher power tractor output.
When I add weight to my combine through bin extensions and larger header, what should I do for my tyres?
To realize that adding considerable weight to a machine due to bin extensions and larger header is an important step toward protecting your tyre investment and avoiding downtime during harvest. The first thing to do is estimate accurately the new weight of your combine. This includes the grain weight, of course. With an estimate of the weight split between axles (may require guidance from the equipment dealer) or an actual weight from scales, you can compare that weight per tyre to the capacity of the tyres on the combine. Your tyre dealer can advise you if an inflation pressure increase will handle the new load or whether you need to move to a larger tyre size or rating.
There is considerable stubble damage to my combine tyres. What can I do to control this problem?
Modern hybrid crops are designed for high yield and resistance to wind. The resulting stocks are stiff and resistant to rot. Compound that with sharp edges left from cutting by modern shears, and you have sharp objects, all in a row, right where you want to run your equipment. If the soil is moist, the stocks usually push over easily, but in dry conditions, the stocks stand up firm to anything coming their way. The tyre manufacturers can make tyre tread compounds very hard, but then cracking from premature aging becomes a factor. Given the investment in tyres on your equipment, it would be best to invest in a push-over shoe for your harvesting equipment to spare the tyres from as much damage as possible. Keep in mind that besides preventing untimely air loss and downtime, good looking tyres will help maximize your equipment resale value.
What is special about 'FI' tyres that came on my new implement?
Since time is money for business these days, the agricultural industry wanted to transport implements from dealer to farm and from field to field at a faster rate. Standard implement tyres had an 'SL' suffix to the basic size (such as 11L-15SL). The SL meant service limited to agriculture and was limited to 25 mph transport speed. Going to higher speeds required qualification to the same regulations that govern highway tyres. To handle this need, a new classification of implement tyre was developed. The 'FI' suffix denotes the highway speed qualified implement tyres can be used to transport implements. Even though the transport speed is less than the load rating on the 'SL' tyres, the in-field load capacity of the tyres actually exceeds the in-field capacity of the 'SL' tyres. These new 'FI' tyres, such as 'F1' 11L-15FI, offer you great opportunity to improve the time efficiency of your operation.
How can I easily estimate the ground bearing pressure of my equipment?
Increasingly, the farming community is concerned about soil compaction that impacts both yield and erosion. The easiest way to estimate the pressure exerted on your ground is to identify the proper amount of inflation pressure needed by your tyres to carry the load and add 2 psi to that inflation value. The extra 2 psi represents the tire casing's inherent stiffness. Proper inflation pressure can be read from the load tables we provide in our Web site and in our Farm Tire Handbook. Your authorized Goodyear retailer can also provide assistance in determining your proper tire inflation pressure. As always, the key to knowing your proper inflation pressure is to know how much load you are asking your tires to carry.