We ran both sets of drag radials first at 20 psi, then 17 psi, and finally 15 psi, with 17
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.
To avoid dripping water on them, Dianna drove around the water box and backed up to start
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.
Although it didn't really jump off the line, Dianna's Chevelle did exhibit a bit of proper
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.