Finally, Nitto Tires added that the sidewall and overall construction of the bias-ply slick is less rigid than a drag radial tire. Therefore, upon launch at a dragstrip, the footprint left by a bias-ply slick can be bigger than its drag radial equivalent. Also, the bias-ply slick being less rigid can be more "forgiving" if a driver spins the tires. However, if the track condition is optimal and well groomed, the rigidity of a drag radial can result in faster performance than the bias-ply slick.
A drag radial is a DOT-approved tire with actual tread that many outlaw street car racers use, while the radial slick looks just like a regular slick, the only difference is the internal construction
We asked our tire manufacturers what they get the most questions about concerning drag tires and they were all fairly unanimous that it came down to tire pressure questions, type of tire for the car's horsepower or race class, and vehicle weight and its effects on tires. We also asked our tire companies if mixing construction types front-to-back is hazardous or not, as we've seen (and I'm sure you have too) Mustangs with bias-ply slicks on the back and their street radials up front.
Mickey Thompson's Kundrick agreed with our statement and told us that a trailered drag car is not a major issue because the car is only going straight down the dragstrip, but Mickey Thompson discourages the idea of mixing tire compounds for street use. "Yes, it is most definitely hazardous," Gullett from Coker added. Whether you choose to run bias-ply tires or radials, make sure the other end of the car has matching tires. The difference in construction makes the tires react differently, even when on the same car, so it can sometimes create a dangerous situation at speed.
Tire pressure questions are certainly at the top of the list, if not the number one question. As racers move forward and adapt to new technology, the radial-constructed drag tires take a different tire pressure than their old-school bias-ply tires they've used in the past.
Kundrick told us that in a racing scenario, when moving from a bias to a radial, the radial will almost always require more pressure to maximize its performance. "In general, when in discussion regarding tire pressure, we would ask two questions that we combine to yield a 'power-to-weight' ratio. Along that train of thought, the heavier the car, the higher the pressure. Also, when asked what air pressure is recommended, we would be likely to suggest an 'operating range' versus a specific number. The range being variable based on the ambient temperature, track conditions, and corrected altitude."
Gullett explains, "Tire pressure depends greatly on the weight of the vehicle. The heavier the vehicle, the more pressure it generally needs to perform at its potential. For vehicles over 3,200 pounds (most average street/strip cars), we suggest starting at 10 psi and adding pressure slowly until you reach the breaking point, in terms of traction. Running the most pressure possible reduces rolling resistance, thus making for quicker times. Radial slicks generally require 3-4 more psi than a bias-ply slick.
"For drag radial tires, such as our M&H Racemaster, you should never run below 24 psi on the street, and keep pressures above 15 psi at the track. The normal range of pressures, depending on the vehicle's weight and suspension setup is 15-20 psi." Weight is the biggest factor. Track conditions also affect how that car hooks, so consider that when you're tuning the air pressure or suspension. Horsepower, obviously, has an effect on overall traction, but the baseline tire pressures are geared mainly toward vehicle weight.
Nitto Tires stated that for on-road pressure, always refer to the factory recommended setting for the vehicle. This ensures a safe and reliable ride on the street. On the track, Nitto recommends starting at 20 psi and decrease/adjust from there. Monitor the tires and wheels to see if slippage occurs. If so, that means that the pressure can be too low. However, there are too many variables to consider having a standard one-size-fits all solution, Nitto tells us. Factors such as temperature, horsepower, weight, chassis, track condition, and more are all contributing factors to finding the optimal tire pressure settings.
"Bottom line is to consider that the tire has the potential of generating a certain level of 'spring rate.' The higher you can run the pressure, the faster the car will go. Go too high and the tire will slip; too low and the tire will change shape absorbing power and potentially deforming the contact patch creating more rolling resistance," Kundrick tells us.
So, you're ready to hit the track with your classic Mustang or Ford and your baby needs a new set of track shoes. Don't worry, we've got you covered. Now that you've read all about bias and radial compounds and how they work, we had our tire companies show us what they offer in both bias and radial slicks, and DOT tires for your classic Ford. We know you want to hit the 'strip and see what your Mustang or Ford can do, and now you'll know what tire will work best for your ride and where to start with tire pressures to optimize your combination's traction. Lower e.t.'s here we come!
By design, the radial slicks are more stable, but you should never have any stability issues out of a bias-ply slick if the pressures are right and you have the appropriate suspension setup. The only reason people have issues with wobble or sway on the top end is related to tire pressure, or mixing bias-ply and radial tires on the same vehicle.
the footprint left by a bias-ply slick can be bigger than its drag radial equivalent

BFGoodrich The BFGoodrich...

BFGoodrich The BFGoodrich g-Force T/A Drag Radial, as the name states, is a radial-construction-based drag tire. The rubber compound is designed from the outset for drag racing, as is the wide/flat tread pattern that promotes traction by putting more rubber in contact with the track surface. Two full-width steel belts keep the tire stable at speed. Sizes range from 14- to 18-inch rim diameters. This is the tire that really kicked off the drag radial market, and it is often used on both drag cars and high-horsepower street cars alike.

Coker M&H Racemaster offers...

Coker M&H Racemaster offers a wide variety of drag racing tires, from regular bias-ply slicks, to DOT-approved cheater slicks and drag radials (shown here). M&H has many decades of heritage and the tires are a popular choice with a wide range of drag racing and street car enthusiasts. The drag radials are available in 15- to 18-inch rim diameters. M&H also has a line of vintage-style race tires, which is perfect for old drag car restorations requiring a specific size, such as 8.00/8.50-14, a popular tire in the mid ’60s.

Coker Phoenix Race Tires...

Coker Phoenix Race Tires offers both bias-ply and radial slicks in a number of sizes and compounds. Phoenix is known for its popular F9 compound, as it proves to be a favorite with hard-core racers. It also offers seven sizes for the front of your car, which feature a bias-ply construction and sizes to fit 15- and 17-inch front runner wheels.

Goodyear Goodyear’s Eagle...

Goodyear Goodyear’s Eagle Dragway Special slick has a long history on dragstrips across America. Today, Goodyear offers the Eagle Dragway Special bias-ply slick and the Eagle Drag Radial slick. The Eagle Dragway Special is offered in 13 compounds, but we’re most interested in the D-3 and D-4 compounds for our needs. Several sizes are available in 15- and 16-inch rim diameters. This is the tire provided on the ’12 Ford Racing Cobra Jet race cars as well.

Goodyear Goodyear’s latest...

Goodyear Goodyear’s latest offering is the Eagle SS DOT drag radial. Available in nine sizes from 15- to 17-inch diameters, the Eagle SS features a unique DOT tire compound with a standard radial construction and unique sidewall styling. The SS line was recently re-engineered and we’ve heard many racers like the results.

Mickey Thompson Mickey Thompson...

Mickey Thompson Mickey Thompson offers the ET Street Radial, a DOT-approved, street-legal drag radial with a soft compound and directional tread pattern for maximum traction. The ET Street is best for auto trans cars according to Mickey Thompson, and is available in 15- to 17-inch rim diameters. The ET Street Radial II, designed for larger wheel sizes and big brake packages is available in 14- to 18-inch rim diameters. These tires are often the choice of street cars with big horsepower numbers. Of course, Mickey Thompson still offers its famous Sportsman Pro bias-ply DOT tires in nearly a dozen 15-inch diameters with matching front tires too.

Mickey Thompson Mickey Thompson’s...

Mickey Thompson Mickey Thompson’s ET Street is a bias-ply street legal (DOT-approved) drag tire. The bias-ply construction is best used for manual trans cars with a standard clutch according to Mickey Thompson. The ET Street requires an inner tube for extra sidewall strength and more consistent ETs. The ET Street is available in 15- to 17-inch rim diameters.

Mickey Thompson The Mickey...

Mickey Thompson The Mickey Thompson ET Drag slick is available in both bias-ply and radial construction, neither of which are DOT legal. These are full-slick drag tires for track use only. The bias-ply ET Drag tires are available in different rubber compounds, while the radial version comes in only two compounds. The ET Drag bias-ply is available in 13- to 16-inch rim diameters while the radial version is available in six 15-inch rim sizes only.

Nitto Nitto’s NT555R is a...

Nitto Nitto’s NT555R is a DOT street legal drag radial designed for compliant and comfortable road use that can double as a drag tire when it’s time to hit the track. The NT555R’s soft rubber compound offers the best in grip and a wide, flat tire tread makes for a superior contact patch while still giving a quiet street ride and the ability to see wet street use. Nitto offers the NT555R in 14- to 20-inch rim diameters.

Nitto The new kid on the...

Nitto The new kid on the block at Nitto is the NT05R DOT drag radial. The NT05R offers improved consistency and controllability with even more dry traction at the sacrifice of more road noise and less wet traction. It is designed for serious drag racers, but can still be used on the street. The NT05R is only available in seven sizes ranging from 17- to 20-inch diameters at this time.

Toyo For DOT-approved street...

Toyo For DOT-approved street use, Toyo offers its line of Proxes TQ drag radials. The Proxes TQ features a drag-racing–specific radial carcass with a soft tire compound and enhanced tread pattern that has a semi-slick inner area for traction with a variable pitch outer area for quiet operation. The Proxes TQ is currently available in six sizes ranging from 16- to 18-inch diameters.

Toyo The Toyo Proxes Drag...

Toyo The Toyo Proxes Drag Slick is a bias-ply drag tire for track use only. It’s designed for Sportsman level drag classes and is consistent in both hot and cold track conditions and can work with small or big burnouts. The Toyo Proxes Drag Slick allows for an increased number of runs before wearing out as well. The Toyo Proxes Drag Slick is available in a dozen 15-inch diameters.