In this month's Tire Talk, we'll evaluate the Bridgestone Dueler A/T REVO tires, a set of Finn F1000 cast-aluminum wheels, and as a special bonus, we A/B-tested and will report on the benefits of installing new shocks. The dampers we road-tested are a set of Tokico Trek Master R/Ts. Our test mule this month was an '00 Nissan Xterra; not one of the best-handling SUVs on the market, but we thought this would be a challenging test case for the new rolling stock and dampers.
Our Xterra test rig racked up 90K on the odometer, and the tires we had on it were severely worn, so we didn't even try to baseline the stock combination. It would've be futile anyway, which is why we threw in the shock evaluation. First we mounted, balanced, and installed the new Bridgestone Dueler A/T REVOs on the FINN F1000 wheels and got a baseline in terms of ride quality and handling without the Tokico shocks installed.
The stock wheel is 15X7 inches, but our replacement was 15x8 inches, which increased the volume of the air space inside the wheel; this required an adjustment in tire pressure. We started with 30-psi cold pressure and noted that road shock attack is more aggressive than when we reduced cold pressure to the factory recommended 26 psi. At 26-psi cold, we observed a 30-psi warm pressure, running at 70-75 mph on the freeway portion of the test loop. With the vehicle unloaded, we wanted to see around 32-psi running pressure, so we bumped the cold pressure up to 28 psi to compensate for the larger volume. Road shocks and vibration were noticeably smoother at 26 psi than at 30 psi, but road feel wasn't as crisp. We seemed to get a good balance of road feel, vague though it was with the worn shocks, and ride comfort at 28 psi. As an aside, tires at 30-psi cold pressures were extremely smooth, if a little too harsh. This confirms to us the claims that Bridgstone technology makes a very concentric (round) tire.
We experienced some oversteer gain with the new tires before installing the Tokico Trek Master shocks. It was hard to distinguish at the time if it was roll steer, or a characteristic of the tires. After installing the Tokicos, we discovered that it was the dead shocks on the vehicle. They didn't control weight transfer on corner entry, so when the body rolled as we began the turn, the sudden weight transfer increased the rear slip angle, turning the vehicle more than the steering angle would indicate. Also, when accelerating off a corner near the limit of traction, we felt a pronounced oversteer. We also found that the road feel came back with the Tokico shocks.
In our lane change test, the vehicle handled OK, although, the lack of body control caused the Xterra to oversteer a little when initiating the lane change, and was significant when attempting to stabilize the SUV after the lane change. This required some steering correction to keep the vehicle from spinning out. After we installed the Tokicos, it was much more controllable and driveable at the limit in this abrupt avoidance maneuver.
The Bridgestone Dueler A/T REVOs are very communicative. They gave lots of feedback (more so with good shocks) on the level of grip available. They growled first, then barked when reaching their limit, and lost grip in a very nice slow decay of traction. The tires were very forgiving, but had a ton of cornering grip for an A/T-type tire.
Both the tires and the shocks are highly recommended. If you're in the market for new tires, the Bridgestone Dueler A/T REVO should be right at the top of your list. And while you're at it, have a set of Tokico Trek Master shocks installed. The combination is a pure joy to drive.
Test Wheel: Finn F1000In deciding what to test for this column, our preference, which we assume most readers are in agreement, is to choose tire/wheel combinations that will fit without interference from the body at all steering angles and suspension motions. In this case, we wanted an aluminum wheel that was reasonably priced with a style that'd look right at home on or off the road, since our test mule was an '01 Nissan Xterra.
The stock wheels were OK, but the 15x7-inch aluminum wheels just looked, well, stock. So we had to change it. The crew at Complete Wheel Source suggested a Finn F1000 as a replacement wheel for the Xterra. It came in 15x8 inches with a backspace that'd work fine on the Xterra, while giving an extra inch of width to the rim. The added width was the perfect size; the measuring rim width was 8 inches for the Bridgestone P265/70-15 Dueler A/T REVO we were testing.
This is a six-lug wheel, but is available in five-lug as well. The polished aluminum surface is accented with cast-in faux bead lock with FINN cast into the surface. The casting work is topnotch, with no flashing or unfinished surfaces or edges. What impressed us most and convinced us of the quality of this cast-aluminum wheel was its nearly perfect concentric rim with imperceptible radial or lateral runout. We've seen more expensive forged units with more runout.
In addition to the quality of the finish work, the centers and hubs are designed to hold the load of a light truck. In fact, the weight rating is cast into the back of the wheel. The ones we used were rated at 3,500 pounds.
FINN F1000 Available Sizes: 15x8: 0mm offset; 15x10: 25mm offset; 16x8: 0mm offset; 17x8: 0mm offset
Test Tire: Bridgestone Dueler A/T REVO Bridgestone's pitch on the Dueler A/T REVO is a standard marketing mix of features and benefits. The features are a little obscure, as they are more technological than observable, but the promised benefits are just what you'd like in a sport truck or SUV tire. The company touts the tire's powerful grip and smooth ride, making it the light-truck and SUV tire that's equipped for the best and worst driving conditions; and says its advanced technology gives superior performance in the wet, the dry, and even the snow, as the tire wears.
The advanced technology that is source of the tire's improved handling in wet or dry conditions and reduced irregular tread wear comes in the form of a comprehensive, innovative tire design method that combines the ideal tread design, casing shape, materials, and construction. This whole regime of chemistry and manufacturing technique is what Bridgestone refers to as UNI-T. With the AQII suffix, the Bridgestone chemists and engineers stuff even more tire design wizardry into the tire.
The new manufacturing techniques are said to produce a rounder overall tire shape that provides better balance for wet or dry handling. In addition, an innovative compound features something the company calls long-link carbon, which offers increased wear resistance by reformulating the compound such that it strengthens the rubber and Super EPC. Super EPC, Bridgestone-speak for a quiver of compound chemistry tactics that consists of Anti-Hardening Resin and Link Stabilizing Agent, counteracts the effects of heat so worn tires have the flexibility needed for wet performance. The Dueler A/T REVO also uses Bridgestone's Dual Layer Tread technique, which has specially treated rubber so that as the tire wears, more of it is exposed, allowing the older, heat-cycled tire to grip the road in wet conditions much like it did when new.
The tread pattern is also a high-tech invention called Hydro Evacuation Surface (H.E.S.). H.E.S. is designed to efficiently channel water away from the tread to reduce the risk of hydroplaning while giving better wet performance. Not only is the tread pattern designed to pump water away from the tread area, it also designed to promote even-surface contact. Bridgestone calls this Consistent Surface Contact (C.S.C) and again is intended to improve dry and wet handling as well as reduce irregular wear and improve ride quality.
One last bit of Bridgestone's manufacturing technical prowess is the Spiral Wrap construction of the carcass. Spiral Wrap is a continuous nylon wrap that encircles the whole tire. This technique provides a higher level of uniformity and helps the tire hold its original shape.
Performance summary: FINN/Bridgestone Dueler A/T REVOWheel: Finn F1000 15x8-inch w/ 4.25-inch backspace; cast-aluminum one-piece; polished aluminum finish
Tire: Bridgestone Dueler A/T REVO P265/70R18 110S M+S. Tread: two-ply steel; two-ply polyester; one-ply nylon; Sidewall: two-ply polyester. Ratings: Tread wear: 500; Traction: A; Temp: B; Max load: 2337 lbs @ 44 psi max air pressure
Wheel/tire weight: Stock: 55 lbs; FINN/Bridgestone: 59 lbs.
Steady state cornering: Excellent grip and feel; good linear response to steering inputs; forgiving at the limit45-mph lane change peak force: 0.88 g
Cornering while accelerating: Lots of grip that's easy to manage while accelerating; tires let you know how much throttle and steering it'll take and are easy and forgiving to balance cornering and forward acceleration; sure-footed
Cornering while braking: High levels of grip with great control; good response to steering inputs with ABS activated
Cold stop, 60-0-mph braking: 0.860 g/139 ft.
Road noise: 65-mph freeway lower than OE; 45-mph smooth surface road noise is noticeably quieter than stock; rough surface quiet than stock. Old blacktop: very quiet; just above wind noise
Ride quality: Moderate
Comment: Significant improvement over stock tires; road shock's attack is muted but not dull; absorbs the energy, but allows enough information to chassis for good road feel
Available sizes:P225/75R15P235/75R15P245/75R16P265/75R16P225/70R15P235/70R15P235/70R16P245/70R16P255/70R16P265/70R15P265/70R16P265/70R17P275/70R1630X9.50R15 LT31X10.50R15 LTLT215/85R16LT215/85R16LT235/85R16LT225/75R16LT225/75R16LT235/75R15LT245/75R16LT245/75R16LT265/75R16LT265/75R16LT265/75R16LT285/75R16
Tokico Trek master R/TTokico has been manufacturing shock absorbers, brake parts, and other hydraulics for more than 50 years and is a major original equipment supplier to a variety of auto manufacturers. Tokico developed the twin-tube low-pressure gas shock absorber in response to automakers' demands for a shock that could provide both good stability and good ride quality. Tokico began working on this technology in the mid 1970s. Since then, much of that technology has been adopted worldwide.
The reason oil is pressurized in a shock is to minimize the negative effects of foaming or cavitation. Oil has some gas or air bound up in solution. When the shock piston moves through the oil, there is a pressure drop behind the piston and the air comes out of the solution and forms foamed oil. For maximum performance and efficiency, the shock piston must work in clear oil.
There are two types of gas-pressurized shocks: monotube high-pressure and twin-tube low-pressure. Generally, a twin-tube low-pressure shock provides a better ride for a given level of control than a monotube high-pressure shock. However, an inexpensive poor-quality low-pressure shock is no bargain.
Tokico's Trek Master combines the company's multistage variable-aperture piston and sandwich valve system with a new base valve design that provides a four-stage, dual-blow-off compression cycle. What that means is the Trek Master gives you some of the best handling, traction, and ride quality available. In addition to the very sophisticated damping system, these shocks feature a low mechanical drag rod guide and piston seal design. Tokico claims this reduces mechanical drag by as much as 65 percent than other shocks, providing smooth operation and long life.