Hankook Tires and GT Wheels - Rolling Stock For Heavy RigsPosted in How To on March 1, 2009 Comment (0)
We go through lots of tires and wheels here at OFF-ROAD. We've shredded, punctured, and worn out rubber from many a manufacturer, and bent up enough wheels to make curbs and rocks shy away in fear when we drive by. We've noticed, however, that we many times use the same few brands for our rolling stock, primarily because we know what we like and we tend to stick to it.
This isn't a good habit for us to get into, because not only do we miss out on products that would suit our needs well, but we also fail to provide informative reports about various products to you, our loyal OFF-ROAD reader. So in the spirit of discovery and good journalism, we mounted a set of Hankook Dynapro MTs on some GT wheels and ripped around in an H1 Hummer to see what happened.
We've always thought the Dynapro MTs looked like a good tire. The blocky V-shaped tread is aggressive and designed to eject small rocks that might otherwise get caught between the lugs. The tires are made in most of the sizes we use (up to 40-inch diameters) and the sidewalls are outfitted with a rugged design that offers extra protection from rocks and other sharp debris. We were impressed, but it wasn't until we looked at the Dynapro's spec sheet that we got excited.
The 37x12.50R17 Dynapro MTs we tested boast 10 plies under the tread and a maximum load rating of 4,080 pounds per tire. Tread depth is a full 21 mm, and the tires can be run at 65 psi. In other words, this is some serious rubber, perfect for heavy vehicles like the borrowed H1 we couldn't wait to flog.
High-capacity tires won't do a heavy vehicle any good unless the wheels they're mounted on are made to carry the weight too. We've known about GT wheels for years - they're the only aftermarket rims factory approved for the H1 and even accommodate an optional CTIS (central tire inflation system) available on some H1s. Even though they were designed for the original Hummer, they've been produced for Ford, GM, Dodge, Toyota, and even Land Rover applications. These 4,500-pound-capacity wheels feature a larger safety bead than any other aluminum wheel we've seen, which helps keep the tire on the rim even at low pressures (GT also produces a beadlock version of the wheel). These are the best wheel option we know of for H1s, but they'd be dynamite on any heavy vehicle that will see both off-road and street duty. The 17x8.5-inch wheels we used are made with about 50 percent more aluminum than comparable rims.
1. The Hankook Dynapro MTs are as aggressive as most other mud-terrain tires we've come across, and the GT polished aluminum wheels have the classic look that we've always loved - plus, they're 100-percent American-made. Aside from the good looks, the tire and wheel combo is perfect for heavy vehicles.
2. We first tested the Dynapro MTs in the sand. Aired down to about 10 psi, they kept the H1 floating on top of the dunes pretty well. We're guessing that a lighter vehicle might have had trouble getting the sidewalls to flex and ball up (which creates a bigger footprint and assists flotation), but that wasn't an issue in this case.
3. We didn't use the CTIS to air down quite as much in loose dirt, but the tires seemed pretty grippy. The owner of the H1, Don Dahlin, told us that the Dynapro MTs seemed to have at least as much traction as the Goodyear Wrangler MTs he'd been running previously.
4. At speed, the tires provided an extremely stable ride. We ran at speeds of about 70 mph on grated (and closed) dirt roads, and we felt safe. We'd bet that a vehicle with long-travel suspension would better help you find the limits of these tires than the big H1 did, but we sure had fun trying!
5. After we gave the Hummer back to the owner, he took it on a 3,000-mile trip across several states. He reported that the Hankook tires were the quietest of any of the tires he's used on the vehicle, and stayed balanced better as well. High-quality wheels like the GTs are important to the balance of the package as well - something many owners take for granted. Tire wear was reported as negligible after this long trip under a heavy vehicle, and that's a good sign.
6. A lot of change can happen in 140 years! On the left, the best rolling stock available in 1870 is visible. The more technologically advanced Dynapro MTs and GT aluminum wheels (with the central tire inflation system installed) better represent how we prefer to roll in these modern times.
What We Thought
We were able to test the tires in sand, loose dirt, rocks, and on a hard-pack grated road (at high speeds). We also logged in some highway and city miles. We ran low tire pressures in the sand, rubbed the sidewalls on plenty of rocks, and spun big donuts in the dirt. The tires were certainly grippy enough, and they resisted damage pretty handily. The wheels and CTIS functioned flawlessly and the polished finish still looked great at the end of the testing.
We learned more about the unique capabilities of this wheel-and-tire combo when we talked to the owner of the H1 a few months later. He'd driven across most of the country and back, and reported that the tire noise was less intrusive than any of the brands he'd used before. The 37-inch tires felt truer and rounder than his previous meats, and sure enough, they seemed more impervious to wear. Turns out there are good reasons for choosing the higher-capacity combo! When we're ready to mount some rubber and aluminum on our next support vehicle, we know who we're calling.