Four small patches of rubber are all that keep your ton and a half Corvette going where you want as it rockets down the road. The horsepower and weight of some C2 and early C3 Corvettes hopelessly outmatched their original tires. If you’ve driven a 425-horsepower Corvette wide-open throttle on 7.75x15 tires you know what I mean. The match between tire and vehicle became closer on late-model C3s as the horsepower dropped and tire size increased, eventually going up to 255/60R15s.
Today’s tires and wheels can bring a higher level of performance to these older Corvettes. We’ll look at the many options for performance tires and wheels for C2 and C3 Corvettes and explore new tire technologies that benefit all car enthusiasts.
Tires look pretty much the same but that belies what lies beneath. The advances in construction and materials constantly increase their performance and life. One of the first popular performance oriented tires for Corvettes and muscle cars was the Firestone Wide Oval. These bias-ply tires rarely made it to 10,000 miles with spirited driving. Now, many radial tires provide a greater level of performance and last 40,000 miles or more.
The advances in technology mean that the tires you buy today will have better performance and better life even if you use the original 15-inch wheels and OEM tires sizes. Plus, now there are radial tires that look like the original bias-ply tires on C2 Corvettes. And for those who just want a period-correct aftermarket appearance for C2s and C3s there are a number of choices, with BFGoodrich Radial T/As and Cooper Cobras being among the most popular.
Plus Sizing – Larger Wheels
When stock 15-inch wheels are used, the widest tires that will fit C3 Corvettes on all four corners without rubbing the fiberglass or the frame are generally 245/60R15 or 255/60R15. Larger diameter wheels will be required to put modern high-performance tires on these Corvettes. Installing larger wheels and lower profile tires is termed “plus sizing.” The challenge lies in finding a good tire width and aspect ratio to approximate the diameter of the original tires.
Increasing wheel size to 16-inch was good 10 years ago but now the choices of 16-inch performance tires that fit early Corvettes have greatly decreased. For example, in the 255/50R16 size, nearly all the remaining tires are for track use. One of the only street performance tires remaining in this size is the BFGoodrich g-Force Sport COMP-2. The good news is that this tire is highly rated.
There’s still a decent selection of 17-inch performance tires that fit C2 and C3 Corvettes. However, the number of choices is likely to decrease. Next, the 18-inch wheels may soon prove to be a better size for these early Corvettes because there are a number of late-model cars that use 18-inch tires sizes that would be a good fitment. Therefore, it’s likely tire manufacturers will continue to offer these tire sizes for years to come.
After deciding what diameter wheel is best, the choices of brands and styles are enormous. Hundreds of aftermarket wheels are on display at the SEMA show in Las Vegas each year. It would be impossible to cover all those new custom wheels here. For the old-school custom look on early Corvettes consider two of the most popular choices: the Torq-Thrust II and the Cragar S/S. And for replicating the original 15-inch Rally style, follow along to see a number of new choices that enable running a wide variety of modern performance tires.
While wheel choice largely concerns appearance, your performance tire choice should be more data driven. There are several specifications that are useful when choosing new tires. Uniform Tire Quality Grade (UTQG) standards were created by the U.S. Department of Transportation (DOT) to provide information on the relative treadwear, traction and temperature capabilities of passenger car tires. These three grades can be found in the specifications for each tire and they are embossed on the tire’s sidewall. It’s also worth noting that all UTQG data is provided by the manufacturer, not the DOT.
The treadwear grade is displayed first and now goes to over 600 for some passenger car tires. A high treadwear grade is of most interest if you drive many miles per year. High-performance tires are often graded in the 300 range or less. Even though high-performance tires wear faster (and have shallower tread depth), the treadwear grade is of little concern for Corvettes that are driven a few thousand miles per year or less because the tires will go past their safe age before they wear out.
The traction grade comes second and now goes up to AA. This grade is of limited use because it only measures a tire’s straight line wet traction. It does not measure accelerating, stopping, or cornering performance on dry roads. Slicks, for example, provide excellent traction at the dragstrip but their UTQG traction grade would be quite low.
The last grade displayed is the temperature grade. It relates to the internal friction and resultant temperature buildup in the tire to help determine its maximum safe speed. The temperature grade of A indicates the tire can be safely run at over 115 mph. The grade of B indicates that the tire will not overheat when run and at speeds between 100 and 115 mph. A separate tire speed rating is used for exceptionally high-speed applications. For example, a W speed rating indicates it’s good for up to 168 mph.
Once the limitations of the UTQG specifications are understood, the need for real world tire information becomes clear. A good source is TireRack.com. On this website you can compare specifications such as tire diameter, tread depth and treadwear on hundreds of tires. That’s very helpful but what’s most valuable when deciding between several tires are the many reviews from car enthusiasts on any specific tire. (For example, the BFG Radial T/A Performance All Season tire has over 500 reviews). Importantly, the reviewer’s driving style and experience with other tires are described along with comments on comfort, road noise and traction.
In addition to the Tire Rack user reviews, you could also talk to the experts at Coker Tire who have personally tested most of the popular performance tires. Both Coker Tire and Tire Rack can ship tires directly to and also offer complete wheel and tire packages (mounted, balanced and ready to be bolted on).
Modern performance tires can make a vast improvement in the safety and handling of your C2 or C3. So it’s not surprising that installing new tires and wheels is one of the most popular performance and cosmetic changes owners make to their vintage Corvettes.
01. A close inspection is needed to reveal that this C1 is sporting a revolutionary new wheel by Deluxe Wheel Company. This 20-inch wheel has an integral 2 1/2-inch whitewall and permits installation of the original 15-inch hubcaps. The 20-inch wheel size ensures availability of a healthy selection of modern performance tires for vintage Corvettes that want to preserve the original look.
02. Restorers know that Coker Tire offers correct Firestone and BFGoodrich bias-ply tires for C2s in whitewall, Redline and Gold Line versions. For drivers who want the stock look but increased performance, Coker also offers BFGoodrich Silvertown radial equivalents, such as this 205/75R15 for the original bias-ply 7.75-15.
03. Coker now offers a FR70-15 Firestone Wide Oval Radial design for owners of 1968-’72 Corvettes that want more performance than the original bias-ply tires. Their new FR70-15 Firestone Wide Oval Radial is available in redline or raised white letter.
04. There are also 15-, 16-, 17- and 18-inch chrome or silver powdercoated Rally style wheels available for those who want to run modern performance tires but keep the stock theme. Original center caps can complete the look and trim rings are available for the 16- and 17-inch wheels. Wheel Vintiques wheels are steel and are made in the U.S.
05. Aluminum polished Rally wheels are offered by Newstalgia Wheels in 15- to 20-inch sizes. These are made by Circle Racing and their centers are CNC machined from billet, as opposed to cast.
06. The YearOne Corvette Rally Wheel from Newstalgia Wheels only comes in 17-inch but is an affordable choice at less than $1,000 for a set of four wheels. These are one-piece cast aluminum with a powdercoated center and machined outer surface.
07. When increasing wheel size, you don’t want the tire to look too small in the car’s wheel opening. The overall diameter of these 255/45ZR17 tires is a little more than 1.5 inches smaller than the original GR70-15 tires.
08. Offset trailing arms enable wider wheels and tires to be run on the rear of 1963-’82 Corvettes. Vansteel offers several models with a 2-inch offset. Their double offset arm has the spring bolthole moved inward 1-inch for even more clearance, but requires the use of a shortened spring.
09. Tires ordered from Tire Rack arrived at my door the next day. Tire Rack can also ship them to your preferred local service center or any of the 7,500 installers they recommend.
10. It’s good to measure the tread depth at the center and at both edges for comparison later. After a few thousand miles, if the tread depth is unequal, and less at the center or at both edges tire inflation pressure should be increased or decreased, respectively. If the tread depth is less at one edge of the tire, camber should be adjusted.
11. Reading this type of tread gauge takes a little getting used to. If more of the number shows, the tread depth is actually less. For example, if the number 9 is just barely exposed, the tread depth is a little over 9/32-inch. If all of the 9 is exposed and it is pushed a bit away from the gauge edge, the tread depth is less than 9/32.
12. Check the date code on your new tires. At the end of the DOT markings, the first two numbers tell the week of manufacture and the last two numbers tell the year. This tire was made the 30th week of 2016.
13. Now it’s your turn. How old is this tire marked 4602? It was made in the 46th week of 2002. And now unsafe. You should not be driving on tires this old. Check your tires’ age … they may be a lot older than you think.
14. If you are a do-it-yourself type, remove the hubcaps or center caps and trim rings before driving to the tire store. This also makes it easy to recheck the torque on the lug nuts after driving the car back home. It’s particularly important to recheck the torque on aluminum wheels.
15. Some tire stores have equipment that automatically measures your tires’ tread depth by lasers. Some equipment may also measure braking at each wheel when the car is quickly stopped.
16. Kauffman Tire stores also measure alignment at no charge and then provide a printout to show when adjustments or repair work needs to be done to preserve the life of your new tires. The right rear camber on this car needs the most attention but that can easily be adjusted at home.
17. The new Hunter Revolution tire changer is so fully automatic that their video shows a tire being changed by a small child. Rollers come down to break the bead of the old tire away from the wheel without contacting the wheel.
18. The wheel should be inspected when the old tires are removed. Moisture inside one tire caused rusting in several spots. This is why it’s important to have a dry air supply for inflating tires.
19. The mounting of the new tires is equally impressive. This machine even has a “bead massager” (I’m not making this up) to ensure that the tire is properly centered on the wheel.
20. This type of tire balancer has a wheel that pushes into the tire during balancing to simulate the deflection on the tire as it rolls down the road. Also note that the wheel is mounted on the balancer by the lug nut holes to simulate its placement and centering when installed on the car.
21. The Hunter GSP 9700 balancer additionally measures wheel and tire runout and the lateral forces generated by the wheel and tire. This can be used to determine where to place each tire on the car to balance or cancel out this effect. Service centers that have this state-of-the-art equipment can be found on the Hunter website.
22. This balancer also shows the operator where to mark the tire and wheel if it is necessary to break the beads and then rotate the tire with respect to the wheel. This is called “match mounting” and is sometimes needed to attain an acceptable balance. Once the marks are aligned, the tire is put back on the balancer and weights are added as needed.
23. The 10-inch tread width of these 255/50ZR16 tires not only puts a lot more rubber on the road, it gives the car a more modern and muscular appearance.
24. The new g-Force Sport COMP-2 tires look great and stick great. The old tires spun in First gear at any rpm with a wide-open throttle and were very slippery in the rain. All that’s changed. BFGoodrich markets these tires as “Ultra High Performance” and based on the vastly improved traction, I won’t disagree with that. I only wish I had put them on my car sooner.
Photography by the Author and Manufacturers