Finding the right tires for a C1 Corvette can be a little more complicated than shopping for modern tires, so we have assembled an easy guide to choosing the proper tires for your Corvette. Whether you’re going back to 100-percent stock or doing a custom combination, tire and wheel fitment is finicky on early Corvettes, so there are a lot of things to consider when it comes to sizing. You also have the choice of bias ply or radial, and then you have the very important choice of sidewall style.
The first thing to take into consideration is the intended usage of your Corvette. If you’re doing a by-the-book restoration, you’ll likely choose a different tire than if you’re planning to drive it on the Power Tour. This decision is based around the tire’s construction, which is something that changed around 1974. Most tires before 1974 featured bias ply construction, whereas modern tires feature radial construction. The two construction types offer two distinct looks, but most importantly, offer two distinct ride qualities that could drastically affect the fun factor when you slide behind the wheel and take a drive. There are pros and cons to both types of tire construction, but it’s important to know the differences to help make your decision.
The term “bias ply” refers to the internal construction of the tire. In a bias ply tire, the cords (plies) run at a 45-degree angle from bead to bead. This diagonal pattern is criss-crossed with each layer of ply cord and creates a strong structure. In the classic car market, bias ply tires feature a narrow tread profile, with a sharp shoulder that usually features a fluted edge, which is commonly referred to as “piecrust”. The narrow tread pattern, and the fact that most bias ply tires mount to narrow wheels makes for a sidewall bulge that is easy to identify.
The major advantage to a bias ply tire is authenticity. All C1 Corvettes came from the factory with 6.70-15 bias ply tires, but there were many variations of style, brand and whitewall width during those 10 years of Corvette production. Thanks to the efforts of Coker Tire, many recognizable tire styles are available, and many of them use the original branding for a truly authentic tire. For decades, Coker Tire has bought and refurbished thousands of vintage tire molds and put them back into production so we can have new reproductions of those original-style tires from the 1950’s and 1960’s. Coker also produces great tires for C2 and C3 Corvettes, but the focus of this article is C1, so we’ll address the other Corvette generations in future articles.
Bias ply tires are strong, but the rigidity offers some questionable handling characteristics if you’re accustomed to driving on radial tires. The construction design places the load on a very small section of the tread surface, which means that bias ply tires do not conform to the road as efficiently as a radial tire. This creates a “wandering” sensation, as the tires tend to follow the ruts and breaks in the pavement. This wandering is not necessarily dangerous, but it requires the driver to pay more attention, especially at highway speeds. The handling characteristics, tread life and traction are disadvantages of the bias ply tire, but purists will choose authenticity above ride quality when faced with that decision.
Radial tires are a popular upgrade for vintage Corvettes, as the more modern construction offers great improvements, including ride quality, wet weather traction and tread life. The advantages are created by the tire’s construction, which consists of ply cords that run 90 degrees in relation to the bead. This radial orientation of the cords applies the load to a much larger section of the tread, which allows the tire to conform to the road surface. This makes for a pleasant ride quality, even on rough or grooved roads.
In most cases, a radial tire will have a wider footprint, even if it is the equivalent size to a bias ply tire. For instance, a 6.70-15 tire (O.E. size) has a P-metric radial equivalent of a 205/75R15 tire. However, the radial equivalent features a wider tread surface by more than one inch. This increased contact patch offers more traction and more stability, while the rounded shoulder provides additional traction in hard cornering situations. Radial tires also feature additional tread sipes, which helps evacuate water from the tread surface, and thus, increases wet weather traction.
The drawback to the wider footprint is the lack of an authentic shape and profile. However, you can get a modern P-metric radial tire with the classic whitewall design. Coker Tire once again stepped into the market to produce a specially made wide whitewall tire with radial construction, a design that did not exist prior to 1994. After Coker began producing wide whitewall radial tires, many other brands became available, giving Corvette enthusiasts numerous brand and style options. In 2013, Coker Tire introduced a revolutionary new tire, called a bias look radial. This tire is a modern radial, but it is built inside a bias ply mold to provide a truly authentic design with radial ride quality. The tire is known as the American Classic bias look radial and it’s available in 670R15 sizing for early Corvettes. Bias look radials are available in wide whitewall, narrow whitewall and black sidewall.
Wide whitewall tires are a trademark of the 1950’s, as car manufacturers offered them as a popular up-sell option. The combination of Corvette’s stylish wheel covers and wide whitewall tires is a look that will never go out of style. Through the 1950’s, whitewall widths shrank slightly, going from three-inch whitewalls in the early 1950’s down to 2-1/2-inch whitewalls later in the 1950’s. The biggest change came in 1962, when Corvette (and other General Motors cars) went from wide whitewalls to one-inch whitewalls. The tire size remained 670-15, but the one-inch whitewall changed the appearance of the car, in preparation for a major body redesign in 1963.
Tire Care
It’s ideal to order tires and wheels together, so the combination shows up at your door, ready to bolt onto your Corvette. If you choose to keep your original wheels, and have the tires mounted and balanced at the local tire shop, always request lug-centric balancing, as opposed to hub-centric balancing. The lug-centric attachment provides the most accurate balancing, as it doesn’t rely on the center hole of the wheel, which isn’t always perfectly true with the outside diameter of the wheel.
If the tires cannot be installed on the car immediately, always be sure to place a piece of cardboard between the tires (this applies only to whitewalls, white letter, redline and gold line) as the black rubber can leave stains on the white rubber. If the tires came with plastic wrapping, keep the wrapping on the tires, until they are ready for mounting and balancing. For whitewall and white letter tires, you can usually expect to see a blue coating on the white rubber, which protects it during transit. The blue coating washes off with soap and water, and the white rubber can be cleaned as often as you see fit. Citrus-based cleaners are advised on the white rubber, as opposed to bleach-based cleaners, which are too harsh.
For cars that don’t see many miles on the road, you may develop flat spots on the tires if the car sits on a concrete floor for long periods of time. Bias ply and radial tires are susceptible to this condition, but flat spots in a radial tire are usually a bit more permanent because of the steel belting that rides beneath the tread surface. To prevent flat spots you can put the car on jackstands or park it on special curved ramps, but our favorite preventative measure is to get out and drive it as often as possible! It’s much better to replace your tires because of worn out tread instead of flat spots or dry rot. No matter what tire and wheel combination makes the cut for your classic Corvette, put them to use every chance you get!
CAPTIONS
001-When it’s time to put new tires on a 1953 to 1962 Corvette, there are lots of choices. Bias ply tires are the authentic choice, but they do not handle as nicely as a radial. This C1 survivor features a set of BFGoodrich 6.70-15 wide whitewall bias ply tires.
002-Even if you’re not doing a pure stock restoration, wide whitewall tires are a great choice for a C1 Corvette. If you’re building a car to drive, radial tires offer the best ride quality, and you can get them with classic wide whitewalls.
003-Bias ply tires are the most authentic option for a C1 Corvette. This example is a BFGoodrich Silvertown 670-15 wide whitewall bias ply tire. During this generation, Firestone, Goodyear, BFGoodrich and U.S. Royal tires were available.
004-This cutaway illustration shows the ply cord configuration inside a bias ply tire. Notice the 45-degree angle, and the criss-cross pattern for each layer of cord. Most bias ply tires for early Corvettes feature a four-ply construction with polyester cord.
005-Coker Tire acquired thousands of discontinued molds and refurbished them for modern production. Examples include tires like this Firestone Deluxe Champion 670-15 wide whitewall tire, a popular choice for 1950’s Corvettes.
006-A cutaway illustration of a radial tire provides a clear view of the radial orientation of the cords. The cord runs 90-degrees from the tire’s bead, and offers a flexible, yet strong design. Radial tires also feature steel belting that resides beneath the tread surface to provide added stability.
007-With a wider footprint, radial tires certainly offer a more contemporary look that fills up the wheel well and provides increased traction. The Coker Classic Star Series radial offers best-in-class performance, combined with the nostalgic look of a whitewall.
008-Whitewall widths were around three inches in the early 1950’s and shrank as the decade ended. Finally, in 1962, the big move was made from wide whitewalls (where the whitewall goes all the way to the bead) to narrower one-inch whitewalls.
009-The American Classic bias look radial has the appearance of a bias ply tire, with the internal construction of a modern radial. The new tire is available in 670R15 sizing, in wide whitewall, narrow whitewall and blackwall forms.
010-Keeping whitewall tires clean is a tough task, but it’s worth it for the classic look. Many whitewall tires feature a blue coating from the factory, which protects the whitewall during transit. Keep the blue coating on the tires until they are mounted, balanced and installed—the coating washes off with soap and water.
011-Mounting and balancing is a very important aspect of getting new tires for a vintage Corvette. Coker Tire suggests “lug centric” balancing, which involves an attachment that mounts the wheel to the balancer with the lug holes, instead of the center hub.
012-This 1957 Corvette features a custom color combination and a few modern updates, including wide whitewall radial tires. While original bias ply tires were sized at 670-15, the modern radial equivalent is 205/75R15. Early Corvettes have very little wiggle room for larger tier sizing without body or chassis modifications.
013-Pictured is a tasteful example of a modified 1962 Corvette, which utilizes an aftermarket chassis and wider rear wheel tubs. These modifications require extensive labor and cost but allow for fitment of much larger rear tires. In this case, the front tires are sized at 205/50R17 and the rear tires are sized at 295/45R17.
014-Although 1962 Corvettes look similar to the previous year, a big change happened with the tires. Narrow whitewall tires took the place of wide whitewalls, which gave the cars a fresh look. This example retains the narrow whitewall look, but has improved handling and ride quality, thanks to the 205/75R15 American Classic radial tires.
