There are three basic types of tractor tires. The most common are R1 (agriculture), R3 (turf) and R4 (industrial).
I own both R1, for field and primarily winter use and R3 for grounds work during the summer to reduce the contact print and allow a smoother ride. On 4WD tractors the same tire types are used on both axles and are size matched by the manufacturer. Mismatching the sizes can damage the drive line by changing the ratio. Matching is so important now that the tractor manufacturers also recommend you match both the size and the tire manufacturer as there are small differences between manufacturers that can cause ratio damage.
Tire pressure is the primary maintenance and easiest thing to check. Information about tires is moulded into the sidewall and includes the tire width, diameter, pressure, wheel size, manufacturer, manufacture date, load capacity and type (bias or radial).
Tires are designed for specific purposes. Surfaces and their “contact print” or area of the tire that contacts the surface is immediately altered by under or over-inflation.
Under-inflation will distort the tire and cause the centre to be concave, decreasing its tread effectiveness and increasing its contact print. Under-inflation contributes to uneven and premature tire wear, overheating and tread separation.
Over-inflation will cause the centre to bulge out and again, decrease the tread effectiveness by reducing the proper contact print. Both affect the tires’ design for stopping distance, load capacity and durability.
If a specific tire is used outside of its designed environment, deflation may assist in its traction by displacing the weight over a larger area. An example would be an R1 tire that is now on soft sand where an R3 should be used. The design of the R3 displaces the weight over a larger area to prevent the tire from sinking in, which is what you achieve by deflating the R1 tire. This is not a recommended practice as once you are unstuck you now are running on an under inflated tire. A common agreement among manufactures is: as oil is to an engine, air is to a tire.
I record the tire pressure on the inside of the hood and on the rims of my tractor wheels with a permanent marker. When I do my daily walk around, before starting the unit, I check all tires. (This is the manufacturer recommended practice.)
Each tire is labeled “MAX ## PSI COLD” which is the maximum tire pressure for the maximum load at ambient temperature before engaging in use. The allowable variance is 10 per cent below MAX. PSI. If in doubt, tire dealers have charts showing the recommended tire PSI for the varying weight.
I have a selection of tire gauges but my favourite is a pencil plunger type. This is inexpensive, accurate, simple to use and very portable. I keep “pencils” in the tractor tool box and the glove box of my truck.
Another type is a small specific plunger gauge with a maximum 5 PSI that is used with low pressure ATV tires.
Tire valves are an obvious place for leaks and as most are exposed to the elements with limited protection, I keep an eye on their condition. Keep them clean and make sure that the cap is in place. Operating without the stem cap will permit debris to accumulate inside the valve allowing corrosion and foreign material to enter the tire.
If I suspect a tire leak, tube or tubeless, I start at the valve, spraying it with a soapy water solution which will reveal a leak by foaming. If that isn’t the problem I remove the wheel and spray some of the solution around the rim both inside and out. A word of caution: if you have a high centre tractor or one with a cab, you should always use axle stands when removing the rear tires. A loss of the jack could result in a tractor roll over.
A “loaded” valve core carrier (i.e. for a tractor with ballasted tires) and stem separated. Note the large bore in the stem for the ballasting fluid.
If the tire valve shows a leak and simply tightening the valve core doesn’t work, the stem should be replaced. This requires the tire bead to be broken away from the rim to facilitate the replacement of a new stem or entire tube, as both are installed from the inside.
There are two basic types of stems: those used for non-loaded tires and those used for loaded (also called ballasted) tires. The “non-loaded” stems are two piece, valve core and stem, the “loaded” stems are three piece, valve core, valve core carrier and stem. The purpose of this is that the small bore valve core mounted in the valve core carrier can be unscrewed from the large bore stem making it easier to pump the fluid into the tire.
The difference between a tire valve stem for loaded tires (left) and a non-loaded stem.
If a leak is the result of a puncture and the offending item is still lodged in the tire, circle it with a crayon and then extract it. As a temporary fix, a tubeless tire can be fixed right on the tractor with the use of a tire plug tool and plug but to do the job properly, the tire should be removed and a patch vulcanized on the inside along with a plug. A plug is also required as the hole leaves a void exposing the cords for digression by the elements. Patches differ for bias and radial tires.
A tire repair kit including a tool, plugs and adhesive. It also shows a selection of gauges.
A self repair goes like this: First place a jack under the axle to support the weight. Next, using the “T” handled plug tool, insert the rough shaft into the hole and work in and out a couple of times to roughen the puncture (and create a better glue adhesion between tire and plug). Slip plug, coated with adhesive through the slotted hole, into the opening. Extract the tool slightly outside the tire. Cut off the plug close to the tread. If the tire is radial, a radial plug is needed.
Because all of the tractors I’ve owned have had tube tires, investing in the equipment required to separate tires from rims is not cost efficient, so for this task, it’s off to the tire shop.
For smaller equipment, such as wheel barrows, the tire can be removed from a solid rim with tire spoons the same way a bicycle, motorcycle or ATV tire is removed. History has taught me that wearing gloves and eye protection is mandatory.
A tire being “spooned.”
With the assembly supported, I insert the spoons between the tire bead and rim about 90 degrees apart and pry the tire over the rim until one sidewall is off allowing the removal of the tube for patching. After patching and replacing the tube, the reverse process is engaged to re- mount the tire. Take care not to pinch the tube or you will be doing the process all over again.
A word to the wise: an extra pair of hands to hang onto the spoons, preventing them from expelling across the shop or through your windshield, is a good idea.
- Dan Kerr