We also installed WeatherTech Side Window Deflectors which reduce wind noise and dust entry when the windows are down. Molded from 3mm lightly tinted, acrylic plastic, they fit our GMC perfectly. We couldn't resist one other WeatherTech product, FloorLiner, which completely covers the carpet in the footwells
Another part of Big Blue's undesirable performance on dirt and gravel roads is poor traction-understandable considering the truck's stock, Bridgestone, LT245/75R16E, on-road tires. We needed more traction on unimproved roads. For increased performance, we looked to Goodyear, the last big American tire company, which recently introduced the Wrangler featuring Silent-Armor Technology, a new, on- and off-road tire. As Covina, California, Goodyear dealer, Tucker Tire Sales, explained, "Silent Armors have a quieter tread design, a layer of nearly indestructable Kevlar, and the Durawall puncture-resistant sidewall Goodyear uses in its extreme off-road tire, the MT/R, and Rim Guard, originally developed for ultra-performance car tires, such as the Eagle F1 GS-D3, which protects wheels from curb impacts
In the quest for traction and looks, we also, went to a wider LT285/75R16D. While those are load range D, and the tires we removed were Es, because the larger 285 supports more weight, we don't believe there will be a performance or safety problem when the truck is loaded to GVW.
Bigger tires need wider wheels, so we added a set of 16x8-inch Weld EVO Cheyenne 8s. Cheyennes are pretty light at 22.5 pounds each, compared to cast-aluminum wheels of the same size. We need all the help we can get because as good a tire as the Wrangler is if you go to a 285/75 from a 245/75, you get more weight. While tire/wheel weights bulked up from 55.5 to 86 pounds each, it could have been worse had we not used EVO Cheyennes.
We tossed the Welds and Goodyears in the back of Big Blue and headed for Tucker Tire's nearby service facility for mounting, balancing, and installation. Leaving Tucker, we didn't drive far before we noticed, in spite of a more blocky, aggressive tread, the Wrangler Silent Armors are no louder than the highway tires we took off.
Once we tried our 2500HD on some dirt roads, the difference in performance was immediately obvious. The Wranglers' more aggressive, on/off-road tread really bites on dirt and gravel roads
Final Actions
Going to a tire that performs better on unimproved roads and significantly enhances appearance forces a trade-off. With the Goodyears and the Weld EVO Cheyennes on the truck, we, again, tested with our VC2000. Big Blue went 15.50 seconds and 92 mph, 0.29 seconds off our previous best. We took an e.t. hit because the 2.3-inch taller tires were like going from the stock, 3.73 rear end to a 3.42. If we do more to Big Blue, we'll change the ratio to 4.10, which should get us back in the low-15s, while maintaining better performance on gravel roads
Our modified Duramax is quicker. In Part Two, it performed better on the chassis dyno. Big Blue's owner, Gary Peterson, reports that over the last six months, in 25,000 miles of work-truck duty, the fuel mileage picked up about 1-1/2 mpg.