June 16, 2005
Pickup trucks and SUVs become less and less like work vehicles everyday. Today, rather than hauling supplies and equipment to the jobsite, they are more likely to see duty as the primary family transport vehicle, or be customized by their owners for looks and performance. Larger, plus-sized tire and wheel packages are common, with custom wheels wrapped in performance tires that have the style and handling to complement how and where the vehicle will be driven.
Performance, style, image and appropriate size availability are all key factors driving today's growing options in the Street/Sport Truck tire category. Here, bold looks, improved handling and sizes to fit larger wheel diameters are key elements. To advance new tire designs in this category, many tire manufactures are applying design elements proven in their performance-oriented passenger car tires, such as aggressive directional tread patterns and summer-only (three season) tread compounds.
Following the trend towards aggressive directional tread patterns, General Tire has introduced the Grabber UHP, tying the heritage of their Grabber light truck family name to Ultra High Performance. To understand how well this was accomplished, Tire Rack team conducted a Real World Road Ride and limited Performance Track Drive, comparing the Grabber UHP with the AVON Tech ST and Kumho Ecsta STX KL12. The AVON tire offers the size lineup, real all-season capability and value pricing, while the Kumho tire has become one of the more popular choices in the category due to its appearance, price point and broad range of sizes. Our evaluation used three identical 2004 V6 Volkswagen Touaregs, fitted with new, full tread depth 255/55/R18 tires mounted on 18x8.0" wheels.
Our 5.6-mile loop of expressway, state highway and county roads provides a great variety of road conditions that include city and highway speeds, smooth and coarse concrete, as well as new and patched asphalt. This route allows our team to experience noise comfort, ride quality and everyday handling, just as you would during your drive to school or work.
Over the variety of road surfaces and speeds of our evaluation loop, the noise comfort of the AVON Tech ST tire was rated best of the evaluation. This tire produced a more disperse, "white" noise which quickly fell into the background amid other vehicle and wind noises. The more aggressive tread patterns of the General Grabber UHP and the Kumho Ecsta STX KL12 both produced distinctive pitches, with the Grabber UHP generating a relatively low tone, while the Ecsta STX KL12 sounded higher up in the range. While not objectionable, the noise from both tires was noticeably more distinct than the AVON.
Over the impacts from expansion joints and patched road surfaces, the Grabber UHP was found to offer the best ride comfort of the three tires in this test, doing a good job minimizing the bump's intrusion into the cabin. The Ecsta STX KL12 and the AVON Tech ST were noticeably firmer, without being objectionable.
During the light handling experienced on our road loop, the General Grabber UHP offered the quickest steering response on initial input, despite also delivering the best ride quality of the group. Traditionally, ride comfort and responsiveness are direct trade-offs to one another. The handling and responsiveness of the Kumho Ecsta STX KL12 felt very linear, and almost as responsive as the Grabber UHP. Road handling of the AVON Tech ST was appropriate for the category, but not as responsive as the other two tires. This is likely due at least in part to this tire's all-season oriented tread pattern, where the sipes and notches used to aid winter traction result in smaller, less responsive tread blocks.
Our test took place during the summer in northern Indiana, and did not afford us the opportunity to evaluate the winter snow and slush traction of these tires.
Our 1/3-mile per lap test track includes 90-degree street corners, lane changes and simulated expressway ramps. Run in both dry and wet conditions, the test track allows our team to experience the traction, responsiveness, handling and drivability normally only encountered during abrupt emergency avoidance maneuvers.
While rollovers can occur with virtually any type of vehicle, sport utility vehicles, pickup trucks and vans typically ride higher off the ground and have a high center of gravity. This makes them more susceptible to rolling over than performance or passenger cars if the driver looses control. Track testing vehicles with a high center of gravity requires proficient driving sensitivity and skills.
However, in order to learn more about the growing number of Street/Sport Truck tire category applications, Tire Rack has selected its most experienced drivers to participate in our dry and wet Test Track Performance Drives. While this reduces the number of drivers participating compared to passenger car tests, it does accurately compare the tires' performance capabilities at their limit.
In dry conditions, the Kumho Ecsta STX KL12 was able to negotiate the slalom (rapid lane change), generated the highest level of lateral acceleration (cornering g-forces), and was able to lap the course the quickest of this test. Steering response was linear and precise. The General Grabber was just behind the Kumho in each area, but when driven at the limit in the dry did not feel quite as responsive to inputs. The all-season oriented AVON Tech ST was surprisingly close to the other two tires, despite feeling somewhat less responsive than the other two tires.
With water on the track, the General Grabber was clearly superior, feeling stable and predictable, and able to snake through the slalom and carve around the skidpad more easily than the other two tires. The Kumho Ecsta STX KL12 may have felt slightly more responsive than the General, but couldn't match the overall grip level. The AVON Tech ST's true all-season compound could not generate the level of summertime traction to keep pace with the other two tires in this test. The measured stopping distance test in the wet paralleled the handling results, with the Grabber UHP stopping the relatively heavy VW Touareg in the shortest distance.
AVON Tech ST (Street/Sport Truck All-Season): The Tech ST is the Street/Sport Truck All-Season tire member of AVON Tyres' family of Tech performance tires. The attractively priced Tech ST is designed to provide flexibility for the drivers of performance pickups, as well as sport utility and sport activity vehicles by providing year-round traction, predictable handling and control in dry and wet road conditions, as well as in light snow.
General Grabber UHP (High Street/Sport Truck Summer): The General Tire Grabber UHP is a Street/Sport Truck Summer tire that was developed for the drivers of sport utility and sport activity vehicles, as well as performance pickups. While branded with the "M+S" symbol, the Grabber UHP emphasizes traction, handling and control in dry and wet road conditions. The Grabber UHP is only intended to be driven in occasional, very light snow. Read more.
Kumho Ecsta STX KL12 (Street/Sport Truck All-Season): Kumho's family of Ecsta (x' ta) performance tires is designed to enhance every vehicle's capabilities. The Ecsta STX KL12 is a Street/Sport Truck All-Season radial that was jointly developed by Kumho's American, European and Korean technical centers to meet the global needs of drivers of sporty pickups and sport utility vehicles. The Kumho Ecsta STX KL12 blends an eye-appealing appearance with year-round performance and traction, even in light snow. Read more.
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