The supremely flexible casing in an all-terrain version
Coming from the same litter as the Pit Bull Rocker we tested for our May '05 issue, the Growler is a "mild" tread design on the same bias-ply carcass. This great casing flexes and conforms extremely well despite the Rocker's very large tread blocks, we found, and the Growler's much smaller tread elements allow even better conformability. However, while a pliable carcass may be the most important feature of a trail tire, the tread still plays a big role, so it had better work well too.
Since the Rockers didn't always want to stay on the beads with pressures in the 3- to 4psi range, this time we opted for Rock-a-Thon bead-lock wheels from Allied (see sidebar). In all fairness, we could run twice our normal inflation pressures in the Pit Bull tires and still get great conformability, so bead locks aren't essential unless you want every bit of available flexibility.
While the Growler handles quite well on the pavement, is very predictable and even relatively quiet, it is still a bias tire with a trail tread, not a radial with a street tread. A tire that works really well on the trail usually suffers accordingly on the street. All that great flex in the tread area that's so helpful for trail use affects rolling resistance, handling and longevity on the highway-and not for the better. So what?
If what you want is a good street tire, there are hundreds of them to choose from. Much like easy trails are plentiful, there are only so many truly challenging trails. If you're looking for a great trail tire, give the Pit Bulls some serious consideration. Sure, they can be comfortably driven on the street too, but it would be a shame to needlessly wear them out on the highway.
If you still insist on doing much street driving on Pit Bull tires, it'll be a smoother ride than what many street radials can deliver since they are quite round and true-once warm, since the durable Nylon construction does flat spot. Our Growlers on bead locks had an average of only 21 pounds of Road Force Variation showing on the Hunter GSP 9700, which isn't even noticeable in a trail vehicle. On regular aluminum wheels, we've gotten Pit Bulls down to a mere 13.75-pound average. This is really good for any 35-inch tire, and especially a bias-ply trail tread.
On the first trail excursion, the Growlers made a lasting impression by getting us up a pretty darn steep dirt and rock hill. First impressions are important, they say, but we went back the next day to take another look at the hill. It didn't look that bad from the bottom, in the dark, but looking down the slope in daylight sure changed the perspective. Now we pretty much agreed with our trail buddy's original assessment of "impossible to climb." The Growler's turf-tire-like tread had done an amazing job clawing its way to the top-better yet, without leaving much in the way of tracks. Thankfully, and contrary to the "Tear It Up" slogan on the sidewall, the Growler doesn't readily disturb the trail unless you spin the tire, which there's rarely a need to do since they work so well. But if you run them at 1 to 2 psi-which there's also no real need to do as they flex so well, even at higher pressures-they leave marks both on dirt and pavement, as the tread squirms an awful lot at such low pressures.
Dirt roads, loose dirt, sand, and other common trail substances were comfortably covered by the Growlers. Based on our experiences with the more aggressive Pit Bull Rocker, we fully expected the Growler to do at least as well, and they did-just with an even more comfy ride. We never got a chance to try sand dunes or mud, but the milder Growler should be even better in the dunes than the Rocker, which was the first aggressive tire we've ever managed to crawl up sand dunes with. In mud, the Rocker would likely outdo the Growler, but not necessarily by much. The 22/32-inch-deep tread may be mild when compared to the Rocker or Mad Dog, but is still more aggressive than some mud tires, and the directional pattern could help in the slop.
We mounted the front tires "backwards" to get an equal opportunity to back out of trouble and possibly also improve shoulder lug longevity in the process. It's said that running implement tires backwards can increase tread life by 20 percent, and it may also work on directional four-by tires.
Taking the Growlers to the 39th annual Sierra Trek provided ample opportunity to pit the Bulls against granite slabs and rock. Again, we were not disappointed. With lots of biting edges on the supple carcass, the Growler easily went where we wanted to go, within the capabilities of the vehicle. Of course, it's hard to go wrong in rocks with 11.4 inches of capable tread, a durometer of only around 60, and a super-flexy casing.