Modern Tire Dealer

OCT 2018

Magazine for the professional tire industry

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Page 51 of 101

M T D O c t o b e r 2 0 1 8 50 distributed uniformly on the complete contact surface of the track with the ground. Studies have shown, however, that this assumption is not the case, and that the largest pressure occurs on the drive wheel… (with) very little pressure applied in between the dolly wheels. Dave Paulk, manager of field technical services, BKT USA, Inc.: e debate between tires versus rubber tracks is ongoing. A lot depends on where and when you are using the equipment. It also depends on gaining flotation and traction in wet ground or reduced ground disturbance and traction in dry dirt. e main difference between tracks and tires is how they distribute weight, and how this benefits you. Tires have footprints that contact the ground during the revolution of the tire. e machine's weight has to be transferred evenly to the ground during these revolutions. e larger the footprint of the tire the more evenly the weight is distributed, and the less ground bearing pressure it delivers. Tracks have a much greater ground contact area that reduces the tractor weight transfer to the ground. us, in theory tracks delivers less pounds per square inch (PSI) of ground bearing pressure than tires. e points of contact of the bogey wheels and drive wheels increase this some. In terms of traction, tracks work better in wet soil. Tires do as well or better in dry soil. Tracks tend to float across the ground in wet dirt, thus not creating ruts. Tires have to work a little harder in wet soil, and can leave ruts. With the advent of IF and VF tires, you can run lower air pressures to give more foot print, traction and flotation. In terms of fuel economy, tracks are designed to work with about 5% slippage. Tires are designed to work with between 8% and 15% slippage, with closer to 8% being optimum. Tracks are possibly a little more fuel efficient with less slippage factored in, but there are other factors to consider, such as the cost of operating and maintaining tracks. Soil compaction has to be considered when using either one. On average, tracks deliver about 4-8 psi of ground bearing pressure to the soil when parked. is can change some when the tractor is under a drawbar load, and because of track stiffness. e points of contact with the drive wheels and bogey wheels increases this some. So, which is better? Tracks definitely have an advantage in wet soil. You have heard the old adage, "If it's too wet in the field, stay out." Sometimes that is not reality, as crops have to be taken out of the field in the fall, no matter the weather or conditions. is is the purpose of tracks on combines and grain carts. e more serious (issue) is the cost of operating tracks or tires. Although the price of tracks has come down a little, they are still expensive. e cost of maintaining the suspension on tracks is expensive compared to a tractor with tires. Scott Sloan, ag product manager/global LSW, Titan International Inc.: Tracks vs. tires has been an ongoing debate in the ag industry for many years. Depending on what side of the fence you are on, each can make the case. But it really boils down to cost. (With) tracks, although they do a fine job in certain applications, the cost to own and operate them always catches up with the end user, from initial purchase cost — $60,000 to $100,000 more for a track machine over a wheeled machine of the same horsepower — to the inevitable maintenance cost on the tracks, which includes not only parts but time to continually lubricate and adjust. ere have been numerous studies that show advantages to both for traction and flotation, again depending on the source. When it comes to compaction, the idea that a track has an advantage is a bit of a misnomer. Flotation and compaction are two different conversations. In studies it has been proven that track machines actually have higher ground bear- ing pressures than a wheeled machine with correctly inflated tires. Tracks machines tend to be heavier than their wheeled coun- terparts. at load is being carried and is concentrated on the bogies and idlers in the track itself, not equally distributed across the track. Since a tire has an air chamber the load is distributed more evenly across the footprint. With the release of the Goodyear LSW1250/35R46 and the LSW1400/30R46, it has become apparent that a wheeled machine can match the flotation of a track machine with all the advantages of a wheeled machine like higher road speeds with unlimited dura- tions. Pulling power is identical between the two when tractors are properly ballasted. We are seeing a major trend moving away from tracks and to the super singles going on in the marketplace. OE's are evaluating and will most likely be offering them in the very near future. ■ James Tuschner has spent 25 years in the tire industry, primarily focused on the agricultural and specialty tire markets. His experience includes time spent at Alliance Tire Americas Inc. (first as director of marketing, then as director of business development) and Denman Tire Corp. He started in 2016. A G T i r e T a l k Michelin says pneumatic tires will transmit up to 29% more power to the ground and are 4 times better at overcoming rolling resistance than tracks, resulting in fuel savings. SOURCE: NEBRASKA TRACTOR TEST LAB, UNIVERSIT Y OF NEBRASKA, 2013 COURTESY OF MICHELIN NORTH AMERICA

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