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Cooper Cobra Tires - Sticky Situation

Do Drag Radials Really Work?

By Mike Petralia

It's ironic how you can make so much power, yet none of it will help you go faster unless it's applied to the ground. The type of tires you run has perhaps the biggest effect on how much of that power gets stuck to the ground. Sure, other things like your suspension, chassis, and even the track conditions all play a big part, but if your tires aren't working, you'll be slippin' and slidin' the whole way down.

Drag radials have been around for quite a while, and they can help you push your traction envelope further using a tire that can be driven semi-regularly on the street. Although no drag tire, radials included, should be counted upon to provide the best traction under all conditions, e.g. rainy days, there are two different brands out there, and determining which set is the best for you has been a tough debate.

We wanted to give the two major contenders, BFG and Nitto (pronounced knee-toe), a run for the money. We installed two sets of identically sized tires, or at least identical in description-more on that later-on a typical, everyday driver just to see how they'd hook.

Test Car
To legitimize this test we chose not to run the tires on a purpose-built race car with trick suspension and lots of power. Instead, we chose a car that gets driven on a weekly basis with totally stock suspension and a mild small-block for power. This way, we'd be testing the tires in a manner to which most of our readers could relate. A big, heavy car like this that's making just enough power to challenge the abilities of regular radials was the perfect choice. To find such a car we went to an old friend. Ernie Nunnes is the owner of C.A.R.S., Inc in near-by Thousand Oaks, California. We first met Ernie when doing the story on Doug Kruse's Vortech-supercharged, carbureted 383 that ran in the November '01 issue. Ernie was the man responsible for selecting the engine's components, and he also assembled the whole thing. We've kept in touch with Ernie and his wife, Dianna, since then, and when we went looking for a car to test the radials, Dianna tossed her keys into the selection pool.

Dianna's orange '72 Chevelle had just recently been re-painted, after a mishap on a rainy winter road, and she was willing to do all the driving, making it that much easier for us to take the pictures. A typical street small-block, with just a few extra power goodies that Ernie had lying around his shop, powers Dianna's Chevelle. The 355 features 11:1 Speed-Pro pistons and World Products S/R Torquer iron heads. An Isky hydraulic 305 Mega Cam moves the valves, and a Holley 750 breathes air into its Victor Jr. manifold. The TH350 trans features a 10-inch B&M converter, and there are a set of 4.10 gears in the stock rearend. The suspension is nothing to write home about, with stock replacement Gabriel shocks and the original coil springs and bushings still in the car.

Track Testing
When we arrived at Irwindale's newly opened eighth-mile Dragway at 3:00 p.m. on a hot July afternoon, track temps were in the upper 130s, and things were typical for a summer day. We planned to stay until the track closed that night so we could get test data ranging from typically poor to somewhat good conditions. Since Dianna was driving and I was taking pictures, Ernie, who is an experienced drag racer that currently runs an 8-second small-block nitrous car and has years of experience in the game, was put in charge of keeping the tires' pressures constant. He and I took and compared notes before and after each pass.

Stock Radial Baseline
Testing drag radials would not be very effective if we didn't know how fast the car ran on its street tires first. Dianna drives around on Cooper Cobra radials (275/60-15), and the first couple of passes didn't reveal anything out of the ordinary with them. At 35 psi and with just a quick spin after the water box, the Cobras ran an average 9.452 eighth-mile e.t. at 75.215 mph. When testing tires, it's important to look at things other than the e.t. and mph, so we compared 60-foot and 330-foot (half-track) times also. The 60-foot times on the Cobra radials averaged 2.235 seconds and the 330s averaged 6.202 seconds, so we had a baseline to which to compare the performance of the drag radials.

BFG Comp T/A Drag Radials
To keep testing consistent we made sure to run the same size tires as the Cobra radials. The 275/60R-15 BFG drag radials improvements were better than expected with an overall average 9.321 e.t., and the average mph was up with the drag radials by 1.42 mph to 76.635. The BFGs also ran the most consistent of any of the tires when we increased or decreased tire pressure. These results were very promising, so we were excited to see if the Nittos could do any better or if we'd reached the pinnacle and were in for a let down.

Nitto NT555R Drag Radials
Again, we used the same size 275/60R-15 tire to keep comparisons fair. The first thing Dianna reported back to us after her first pass on the Nittos was "They felt more stable at the top end of the track and I'd feel better driving on the highway with them over the [BFGs]."

Performance with the Nittos backed up Dianna's claims and helped the Chevelle run its quickest e.t. and fastest mph of the day. Averages with the Nittos were: e.t.=9.329, mph=76.98, 60-foot=2.25, 330-foot=6.143, which was surprisingly worse than the BFGs by a small margin. The Nittos did, however, beat the BFGs in top speed by a small margin. Perhaps there's a correlation there between the added stability that Dianna felt with the Nittos and the extra mph they were able to produce. There's also no denying that the Nittos produced some of the best e.t.'s of the test, with the exception of the quickest 60-foot, which went to BFG.

The bottom line here is: If you're going to race, either drag radial will help you go faster than your stock tires will. However, because drag radials are not designed for everyday highway use and will wear out quickly on the street, you shouldn't count on them for your everyday transportation.

Eighth-Mile Radial Tire Testing
We tested during a Thursday open test-and-tune session and had to share track time with 100s of other racers. Several things' going wrong blew some of our runs, and we tossed those results out. Below are the results of the two-best runs for each set of tires, which we used to calculate the final statistics.

Cobra Cobra BFG BFG Nitto Nitto
1 2 1 2 1 2
60' 2.242 2.228 2.240 2.193* 2.304 2.196
330' 6.140 6.265 6.152 6.106 6.192 6.095*
e.t. 9.376 9.528 9.359 9.283 9.405 9.253*
mph 75.67 74.76 76.17 77.10 76.07 77.89*
psi 35 35 20 17 20 17
Cobra BFG Nitto
60’ 2.235 2.216* 2.25
330’ 6.202 6.129* 6.143
e.t. 9.452 9.321* 9.329
mph 75.22 76.64 76.98*
* indicates best runs

Tire Specs
BFG Comp TA Drag Radial
Size: 275/60R-15
Tread depth: 1.875, (1.900 as measured)
Diameter: 28"
Tread width: 8.9"
Section width: 11"

Nitto NT555R
Size: 275/60R-15
Tread depth: 1.968, (2.055 as measured)
Diameter: 27.75"
Tread width: 8.5"
Section width: 11"

One Parkway South, Dept. SC
SC  29615
1201 Shaffer Rd., Dept. SC
Santa Cruz
CA  95060
Irwindale Speedway
13300 E. Live Oak Ave
CA  91706
Weld Racing Wheels
933 Mulberry Street
Kansas City
MO  64101
Nitto Tires
6261 Katella Ave., Dept. MMFF
Suite 2C
CA  90630
801 S. Victory Blvd., Dept. SC
CA  91502
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By Mike Petralia
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