Pit Bull Growler Tire TestPosted in How To: Wheels Tires on February 1, 2006 Comment (0)
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.
In an attempt to whip these Pit Bulls we tried climbing a 28- to 34-degree slope of freshly graded alluvial dirt. It was mostly deep silt, actually, with some rocks and branches here and there. An initial run with 10 psi in the front and 8 in the rear (our normal street pressure) only got us about 50 feet up the slope, but that's what the Klune Rapid Air Down valves are for-to get lower pressures really fast. At the other extreme, with 2 psi front and 1.5 rear, we managed to crawl (speed obviously didn't work at all in such powdery dirt) to about 140 feet. Not reaching the 250-foot crest was quite disappointing-until we learned that the 700 HLT Deere that had just brushed the slope couldn't make it back up on that portion either. Guess we can't ask for much better than bulldozer traction.
In case somebody doubts the steepness, we later drove around and descended the slope on a dare by the 'dozer operator-only to lose an inner bead on a front tire from the severe weight transfer. Looks like 3 psi might be the minimum for Pit Bulls with Allied aluminum bead-lock rims.
So far we can't fault the Pit Bull tire's pedigree. It's an excellent casing for trail use, amazingly true, and with a choice between three tread patterns. Sometime soon we'll let you know what happened when we tried the third member of the Pit Bull family ... the Mad Dog.
Based on our experiences with the Pit Bull Rocker tires, which didn't always remain on the bead at the pressures we like to run, getting a set of bead-lock wheels for the Growlers kind of made sense. Of course, bead locks are better anyway, right? Well, in our opinion they aren't necessarily any better than a regular rim with good safety beads-at least not on our vehicle-and for a number of reasons. Having to remove or tighten 32 or so bolts while mounting or dismounting a tire is no fun. Not that using Tyrepliers, tire irons, and/or a hammer is that much fun, either, but it's a lot faster. Usually, bead-lock wheels are also impossible to get a Road Force Variation reading on with the Hunter GSP 9700 balancer, which means we can't balance them properly. Plus, and this we think is the biggie, the typical bead lock forces the tire bead into a shape it was never intended to have, and a common side effect is leakage.
Allied's Rock-a-Thon wheels eliminates most of the aforementioned issues by using a ring with a rolled lip that is formed much like the bead of a regular wheel. We've had good luck with the Rock-a-Thon design before, never experiencing any air loss or damage to the tire, so when Allied released the aluminum version, it seemed like a pretty appealing solution.
Overall, we're very happy with these wheels. Especially after finally being done torqueing, retorqueing, and then re-retorqueing the rings. Air stayed in, the tires stayed on, and they were easily balanced (we eventually managed to lose an inner bead, although that doesn't seem to be a wheel problem).
Aluminum wheels help keep the unsprung weight down, but at 35 pounds, these are still quite heavy for an alloy wheel. And, as some thick-centered aluminum wheels do (these centers are a whopping 2 1/4 inches at the wheel hub with 3.5-inch backspacing) they require a really thin 13/16-inch socket for the lug nuts, even when perfectly clean.
A nice surprise was that the Pit Bull tires and Allied wheels seem to be made for each other. The tire centers very easily on the wheel, so there's no need to fight the bead versus the bead-lock ring since the rim guard automatically positions it perfectly. On the flip side, between the Pit Bull tire and the wheel design, it is impossible to use clip-on weights on the inside. While not being huge fans of bead-lock wheels in general, we really do like the Allied Rock-a-Thon approach as that design does away with most of the drawbacks.
Tire: Pit Bull Growler
Type: Bias ply
Load range: C
Max load (lb. @ psi): 2,725 @ 30
Sidewall: Four-ply Nylon
Tread: Four-ply Nylon
Approved rim (in.): 10-12
Tread depth (in.): 22/32
Tread width (in.): 11.40
Section width (in.): 15.07
Overall diameter (in.): 35.50
Static loaded radius (in.): N/A
Revs per mile: N/A
Weight (lb.): 68
Test vehicle/weight (lb.): Jeep CJ, 3,200 pounds