Upsizing your vintage Piper wheels and tires.
A cub is a young bear as well as the mascot for early Piper airplanes. Today, up to 79 years from their birth, many of these once-youthful Cubs (and Cruisers, Clippers, Pacers and Vagabonds) are getting a bit grizzly.
After decades of landings, good and bad, an old Cub’s legs may be in need of some renewal. Vintage drum brakes, which never were the best, may have lost their grip with age; wheels can become corroded and wobbly; classic fat 8.00-4 tires are increasingly hard to find and painful to afford.
Supply and demand have changed
Decades ago, when the time for a tire change came, most Cub owners just asked their local mechanic to pull a tire off the pile and put ‘er on. Tires for Cubs and Clippers were readily available, made by various manufacturers, and reasonably priced.
But today, Goodyear is the only manufacturer of 8.00-4 tires, and they cost more than $300 a tire. If you need a tube for that tire, add another $140 to $150.
Faced with the possibility of a $900 tire change, many vintage Piper owners are spending a few extra dollars upfront to upgrade the landing gear to accept more reasonably priced 6.00-6 tires.
The upgrade doesn’t only save money on future tire changes; the installation of new tires, wheels and brakes offers owners many benefits in increased safety, durability
and reliability.
A note about tire sizes
On tires with a Type III size classification (for example, “8.00-4,” or “6.00-6,”), the first number is the tire’s section width—that’s the widest point of its outer sidewall to the widest point of its inner sidewall when mounted on a wheel. The second number is the wheel rim diameter that the tire fits.
With Type III tires, there is no indication of the overall diameter (i.e., how “big” the tire is); you have to look that up in the specifications for your aircraft.
To complicate matters, tires and wheels use different designations. A four-inch wheel for a vintage Cub is an 800×4 wheel, while the tire is an 8.00-4. Maybe the tire and wheel manufacturers should have communicated way back when it all started?
Classic Cubs, early Super Cubs, and various vintage Piper aircraft use tires that are 8.00-4, so that means they are about eight inches wide and fit on a four-inch wheel. The precise size depends on the weight of the plane, the rim, and the inflation, and may vary by about half an inch.
For aircraft owners who want to change from the classic 8.00-4 tire to today’s more common 6.00-6, it means you’re changing from a four-inch rim to a six-inch rim, and the tire is two inches narrower.
Reasons to consider a change
The first Piper equipped with the 6.00-6 tires and six-inch wheels was the Piper Tri-Pacer introduced in 1951. In part due to the popularity of training aircraft with tires in this size, numerous tire manufacturers offer a selection of tires with different treads, different numbers of plies, and various prices.
To make the switch to 6.00-6 tires, you must change to six-inch wheels—and to do that, you must change the brakes, too. That could get expensive, but considering that 8.00-4 tires cost about $360 a pair more than 6.00-6 (without tubes), it might make financial sense.
Do you use your plane for training and need tire changes often? Are you satisfied with your airplane’s braking ability? Does the aircraft hold in place during a runup? Are your wheels corroded or cracked? Do you need to replace any other landing gear parts? Are you thinking about flying into the backcountry and might need bush tires, or even tundra tires?
Besides addressing any specific issues with your particular aircraft, changing to six-inch wheels has numerous advantages. With any type of brake, disc or drum, a larger diameter provides better braking—and modern disc brakes are certainly a far more effective design than 1950s-era drum brakes.
If you get a flat tire away from home, you’ll be lucky to find a repair station with an 8.00-4 tire when you need it. With overnight shipping, that’s not quite the problem it was decades ago; however, there’s only one tire that’s approved for a four-inch wheel.
If your favorite aviation parts supplier is out of stock on the tire, you’ll be calling around the country to locate one. And in years to come, there’s a real possibility that 8.00-4 tires will get harder to find, not easier. So why not upgrade all your landing gear parts, brakes, wheels, and tires at once?
A bolt-on kit is available
The engineers at Grove Aircraft Landing Gear Systems, a family-owned business based in El Cajon, Calif., have developed a solution to the problems of aging four-inch wheels and brakes.
Grove Aircraft offers a bolt-on conversion for vintage aircraft to upgrade to modern six-inch wheels and disc brakes for many vintage Pipers, from J-3s up to PA-20 aircraft.
The price for Grove’s conversion, which includes two new wheels (either aluminum or magnesium), disc brakes, mounting hardware, and brake line fittings, costs $1,689.
If you add together a new pair of pricey 8.00-4 tires (research shows a single new tire and tube runs between $466 and $555), plus any extra repair, such as a new four-inch wheel at $450, or a standard brake job that can cost several hundred dollars, then the upgrade to six-inch wheels and tires may make good financial sense.
For a one-time cost of $1,689, you get the option to use less expensive tires with the benefit of better braking.
The conversion kit from Grove is simple enough for the average pilot to install, with parts that bolt on to the existing landing gear attachment points. However, all work should be supervised by a licensed A&P mechanic and must be inspected and approved.
Other wheel conversions
Even if you already have six-inch wheels, it’s important to note that not all systems are approved to take larger tires.
The Grove six-inch wheels have STC approval to accept many tire sizes, including 6.00-6, 7.00-6, 8.00-6, 8.50-6, and 26×10.5-6 tires—and numerous tire manufacturers make them. With these wheels, you can customize your tires to your flying—or more accurately, your landing—needs.
Several other companies, such as Cleveland Wheels and Brakes (a division of Parker Hannifin Corp.), offer STC’d six-inch wheel conversions for Piper airplanes, too.
Each manufacturer comes with an approved tire size list, so be sure that the tire size you plan to use is listed before you buy a wheel conversion system.
Ease of installation
Rick Hannemann, of Sherwood, Wis. recently used the Grove wheel and conversion brake kit on his restoration of a 1954 Piper L21-B Super Cub, a military version of the basic Super Cub.
He reports that the installation was simple to perform. “Everything was in the kit and just bolted on,” Hannemann explained. He plans to mount 8.50-6 tires on his new wheels, a good choice for landing on grass airfields, his type of flying.
“I made this change for better braking and due to the lack of parts for old drum brakes,” Hannemann continued. “I know if I did have a problem , I could call up Robbie directly; he cares about airplanes and his customers.”
With new tires, modern wheels, and brakes, vintage Piper aircraft can keep landing and rolling reliably as long as they can fly.
Dennis K. Johnson is a writer and a New York City-based travel photographer, shooting primarily for Getty Images and select clients.
Send questions or comments to editor@www.piperflyer.com.
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