In our wheel business, we get asked for tire recommendations all the time. Many times, people may be new to the performance car hobby, or new to drag racing. Maybe they have taken their car out to the local drag strip, and went home in frustration. Their cars didn’t perform up to the magazine quoted expectations perhaps, or maybe their driving skill was overestimated. This disappointment happens all the time, across the country, at every track. You may have even seen YouTube video proof of some impressive cars running some dismal times.

Bench racers and those with little racing experience are usually the most critical about these poor-performing examples. They flock to their car forums, citing these drag racing video atrocities as gospel and examples of best-effort runs. But, those of us who do spend too much time at a drag strip, understand all the variables which can affect the time-slip data. Hopefully this little introduction on tires can educate about one aspect of comparisons: Traction.

While some would argue that having equal tire types makes the cars equally capable, that isn’t entirely true. This would also require the same track, same day, and a similar transmission format. Every track in the country has varying levels of surface preparation. Some tracks are historically sticky, while others feel a lot like launching on a gravel road. Having a sticky set of tires on a poorly prepared track surface, doesn’t really help as much as having those same tires on an exceptionally prepped track. So, tires and track prep are both equally important factors of traction, as well as time-slip potential.

For those newer to drag racing, ET (Elapsed Time) is the amount of time that your vehicle moves from the starting line, and crosses the finish line. The biggest impact in ET, is reducing the 60′ time. This is the amount of time your car moves from the starting line, to the first sixty feet of the track. This little bit of data is highly overlooked by the magazine, but you should understand that it is far more important to know than the common “0-60 mph” data.  The 60′ time tells us how well the car takes off from a stop, and also tells us how much traction the car had. It can also give us some insight about how well the racing surface was prepared. How much does that 60′ time matter to the final ET on the time-slip? Generally, we can estimate that every tenth (0.10 seconds) that you can shave from the 60′ time, you will be rewarded with reducing the ET by 1.5 times.  So, every 0.10 off of the 60′ = dropping the ET by 0.15 seconds.  An example:

A vehicle runs 11.0 @ 126 mph with a 1.9 second 60′ time. If this vehicle had instead run a 1.6 second 60′ time on that pass,  his 60′ being 1.9 – 1.6 = 0.3 seconds better, the ET result might end up as 11.0 – (0.3 x 1.5) = 10.55 @ 126 mph.

This is why 60′ is so important. To most of us that actually drag race cars, the time-slip data means nothing without the 60′ data included. Any savings in the 60′ time, results in improving 1.5 times that value in the final ET.

So, lets get back to discussing traction and tires. Want to improve your chances at getting a better ET? Buy some drag radials or drag slicks. This might require a different sized set of rear wheels on your car, if the size you need isn’t readily available. Your car should be capable of shaving an easy 0.1 to 0.2 seconds off of the current 60′ time, if you move from normal street tires to drag radials. This will make a crappy prepped track feel more like an average track, and it will make an average track feel more like an excellent track. You will be less likely to get stuck at the starting line, peeling out, wheel-hopping, or aiming at a railing. You will then enjoy more time accelerating in control, letting the car and driver run to both of their own abilities. Here is a chart I put together, comparing how DOT drag radials and drag slicks are better than normal street tires. Keep in mind how these reductions in 60′ times will play out (1.5x) on your time-slip. The colored boxes indicate the quality of the track surface preparation. Most tracks across the country are “Average”. A track prep of “Excellent” usually only occurs during an event, or a private track rental where extra VHT is sprayed down on the surface.

sixty-footYou may have noticed that I provided two different charts, one for manual transmissions, and another for automatics. The reason for this is because it is more difficult to launch a manual car from a stop. Not so much about driver skill, but how the two cars are mechanically different. The automatic has a few benefits that help improve traction and acceleration from a stop. First of all, an automatic transmission with a viscous coupling between the engine and drivetrain, produces less shock loading when you stab the throttle. The fluid coupling in the torque converter helps absorb some of that shock, which keeps the tires from reacting with a hard initial bite. Dumping the clutch in a manual is about the hardest shock load that any vehicle can produce, and is notorious for making the tires spin. You would need excellent track conditions and a drag slick, in order to dump the clutch in a manual car. But, be warned that your drivetrain (transmission, driveshaft, rear axle of half-shafts) will likely disagree with that effort, and crumble somewhere. The best launches in a manual come from slipping out the clutch at higher rpm, while trying to prevent excessive tire spin or the nose of the car bogging down. It is a delicate balance of both. The automatic car driver only has to focus on controlling throttle and spin, making it much easier and consistent. The other benefit of automatics, is that they usually have a more aggressive 1st gear ratio, compared to their manual versions of the same car. This more aggressive 1st gear ratio in the transmission/rear axle puts the vehicle at a higher rpm off the line, likely making more torque/horsepower off the line. Yet another benefit that most automatics have is that they are equipped with a torque converter within the transmission, which can effectively multiply the torque output of the engine. The biggest gains in 60′ time come from automatic cars with custom torque converters installed, which allow the cars to take off at higher rpm than factory torque converters. Generally speaking, automatic cars usually get an easy 0.10 second advantage in the 60′ time, compared to a manual car, given equal tires. That usually results in an ET that is 0.15 to 0.20 seconds better.

This doesn’t mean that manual cars are worse at drag racing, it only means that the driver has to be better than average. When comparing both stock non-modified vehicles with different transmissions, you’ll find that they are typically both capable of cutting similar 60′ times on drag tires. It is just harder to achieve that excellent launch with a manual. Those people who like to claim that automatics are “more consistent” aren’t including the driver in their statement. A manual driver can become very consistent, given enough practice. The cars themselves are very consistent, regardless of transmission type. The drivers might not be as consistent. Don’t blame the car for that! Go practice.

I hope this article has explained a little about how tire choice, track preparation, and transmission choice all affect traction. If you have any comments or questions, ask below. “Spinning isn’t winning!”