Modern Tire Dealer

JUN 2019

Magazine for the professional tire industry

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Page 53 of 89

M T D J u n e 2 0 1 9 52 ing this time, the "W" type became more popular and the preferred type for many farmers around the world. Today in many regions, the R-1W is the "standard" pattern with some tire lines only available in the R-1W pattern. Let´s look at the differences between R-1 and R-1W in field applications. Soil types are quite individual. Even the same soil type can have different characteristics depending on the thickness of different soil layers, the distance to harder underground layers, and individual and changing weather conditions that impact humidity content. A general recommendation for R-1 or R-1W based only on soil type cannot be made. As the "W" for "wet" says, 20% more tread depth shows significant traction advantages, especially on wet soil types where the lugs sink completely into soil. is additional traction is only given if the soil between the lugs is compressed properly, though (see illustration on this page). Another factor that needs to be considered for the choice between R-1 and R-1W is the application. On many soil types, especially when wet, the "W" type can generate better traction. But for many applications, the traction is not the limiting factor, such as in seeding applications or PTO-driven implements. Here, a wider and more even footprint of the R-1 or even a partly worn tire causes less impact to the soil. One quite special and sensitive applica- tion is the grassland operation, where deep and sharp lugs can cut the turf surface. e effects from this may make the track areas unusable if mud or earth could be picked up in the silage and harm the fermentation. NORBERTO HERBENER, OE applica- tions engineer, Trelleborg Wheel Systems Americas Inc.: First what is a R-1, R-1W, R-2, HF-1, F-2, etc.? It defines the tread pattern of each tire and follows norms/rules established by TRA (USA) and ETRTO (Europe). R-1 and R-1W are the tread patterns used mainly for traction in agriculture and have the typical lug type design. e main difference — defined by norms — is that the lug of an R-1W tire is 20% taller than the lug of an R-1. R-1W is an evolution of the R-1 that started in Europe, as the soil conditions there are normally more humid than in the U.S. From there the "W" in R-1W means "wet." Each tire manufacturer has its own lug design — width, length, angle, shape, quantity — and follows its experience and development to provide the best traction capabilities in each soil condition. (One) advantage of the R-1W is as the lugs are 20% taller (with) a flatter profile, the tire has a longer and more even lug wear life as a conventional R-1. ere are some cases where an R-1 lug height design performs better than an R-1W. is is the case with sprayers and spreaders. is equipment is traveling at high speed with full load on the road (hard surface) where all the pressure is on the lugs only. is high lug movement on hard soil generates higher amount of heat… accelerating the wear of the lugs. Finally, it has been a custom to use the R-2 design (taller lugs) in muddy conditions like in rice fields. e traction performance and grip are superior in these muddy fields, but are not adequate at all for not so muddy soil conditions or road transport. e lugs would suffer high stress, bend with higher damage possibility, (and experience) higher wear and (provide a) very uncomfortable ride. JIM ENYART, technical manager, CEAT Specialty Tires Inc.: e reality is that when comparing tread depths between different product lines from the same manufacturer or from different manufacturers, there are most likely other design differences than just the depth of the tread. ese differences should be a primary concern in the buying or selling process. Tread depth should be a secondary concern. e primary objective should be to iden- tify the best product for the application, period! Making the best choice can only be achieved by identifying the application as well as the features and benefits that are needed or required. Does the specific application require increased load carrying capacities, high speed capabilities, maximized traction, flotation… or does it just need to hold air for the application? e application and features required should drive you to the best product. e answers may lead you to bias, radial, high speed, flotation, row crop, IF, VF or even IF CFO product lines, among others. In the majority of cases, multiple tread depths are unlikely to be a factor in making the purchasing decision. No farmer plans to operate their equip- ment in wet, muddy conditions, but when they have to, they would be better served with R-1W's over R-1's due to the additional traction the deeper lugs can provide. It's much better to be prepared with the deeper tread depth radial tires for wet conditions because down time during harvest season can really hurt the bottom line. If the soil is too dry, or the ground underneath the loose soil is too hard, less tread depth will compress the loose material in the interlug section a little more than more tread depth. In this illustration, note the compression difference in this situa- tion between the R-1W (top) and R-1 (bottom). COURTESY OF CONTINENTAL TIRE A G T i r e T a l k

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