Quality Counts
Sticker shock is rampant these days, and aircraft tires are no exception. Ten years ago, the list price on four main tires for a King Air 200 with standard gear ran $2,900 – now it’s $4,000. I am speaking specifically about Goodyear tires, which have always been my preference because they last longer than Michelins.
Whenever my customers engaged me in the debate of the expensive, longer lasting tire versus the less expensive, short-lived one, I told them this: It takes me the same amount of time to change a cheap tire as it does to change an expensive one. If the cheaper tire wears out faster, it means you’ll be back in my shop that much sooner for another tire change. The money saved on an inferior part is lost on the labor required to change or repair it more often.
The problem right now is finding Goodyear tires. With this topsy-turvy, COVID-crazy economy, the Goodyears have become very scarce. Michelins, however, are in good supply. It appears that Michelin is happily meeting the demand and cashing in on a good opportunity because they raised their price. At this moment, Michelins cost more than Goodyears.
Some shops have managed to keep a few Goodyears in stock. If you know you are going to need new main tires, start calling around now to see who has them. I have seen the supply of Goodyear tires ebb and flow before.
To Recap (or Not)
Recaps (retreaded tires) are another option. The maintenance manual doesn’t recommend them and neither do I; the manual, however, allows the recaps if they come from an FAA-approved source. If you are going to use recaps, pick your supplier carefully. And don’t get too giddy over the few hundred bucks you save on retreads, because when a retread busts apart on landing it’s going to cost you far more than you ever imagined. Your flaps are down for landing, and the exploding rubber projectiles rip through the flap structure like shrapnel. The repair/rebuild of your flap will cost many thousands of dollars.
Inflation and Wear
As with your car, improper inflation is the primary cause of uneven or premature wear on your King Air tires. The maintenance manual gives all the pertinent tire pressures for each King Air model; if an STC has been performed (e.g., tundra tires on a B200), it will specify the pressures to be used. The manual also states when to check your tire pressures and when not to check them, which is when they’re hot.
New tires will stretch a bit in the first few weeks after installation, so they will lose a little pressure. Watch them closely and expect to add nitrogen more than once. If a new tire goes flat, it is usually because of a pinched O-ring. Even the best mechanics pinch an O-ring from time to time when putting the wheel halves back together. It is rare to get a defective tire, but if that happens, the tire should be returned for warranty replacement.
The one tip I offer King Air owners on tire inflation is to keep the main gear tires on the high side – about 5 pounds up. If the manufacturer suggests a range of pressure (say between 100 and 110 psi), choose the higher number.
My observation over the years is that all King Airs sit better on the center of the tread with about five extra pounds in the main tires. This is especially true for King Airs that are routinely operated close to gross weight. I also found that the customers who got the most wear out of their tires were the ones that monitored their tire pressures and kept the mains at the extra 5 pounds up.
Nose Tires
Nose tires are not subject to the punishment of landing. They should last you about 1,000 hours unless the aircraft sits outside. The tip I just mentioned about keeping tires at 5 pounds up is for main tires only, not nose tires. Over-servicing the nose tire causes premature wear in the center treads.
Torque Knees and Uneven Tire Wear
If I’m looking at a King Air with dual truck main gear (the model F90, 100 and up) and I see tires that are worn prematurely around an outside edge, I want to take a look at the landing gear. The tire wear on a new King Air is usually very even; but as the years go by and the landing gear goes through an overhaul (or two or three), sometimes the “toe in” of the main gear can be off.
Too much “toe in” or “toe out” will cause your tires to wear too fast along one edge. If you see this on your main tires, have your shop check the washer arrangement on the torque knees and also have them check for excess play at the center point of the torque knees. Either one of these situations (improper washer setup or too much play) will cause uneven and premature wear on your main gear tires.
Unfortunately for you model 90 drivers, the main tires on the 90s tend to wear unevenly. I can’t tell you exactly why and I don’t have a remedy for it. It is what it is.
Flat Spots and Double Trucks
Imagine the tires on your R/H gear are about 75% worn and you flat-spot the outboard tire. Many pilots expect to replace the damaged tire only, but the proper thing to do is replace both tires. It may look like your maintenance provider it trying to jack up the bill, but they are saving you money in the long run. If you install a brand-new tire right next to a worn tire that’s lost three-fourths of its tread, that fat new tire is begging to be squared off!
I had a customer do exactly that – he squared off a tire on his R/H gear but would only replace the one he flat-spotted, thinking he’d save a few bucks. Three months later he was back with another squared off tire on the R/H side; it was the new tire. Again, he had me replace just the flat-spotted tire, and then he promptly squared off that new tire. Finally he got the message and allowed me to install two new tires on the R/H side. That solved his tire problems and I didn’t see him again until his next Phase came due.
The maintenance manual specifically addresses this issue and stipulates the tires on dual truck gear to be matched in both manufacturer and inflated diameter. The maximum allowable difference between the inflated diameters of the two tires is 0.25 inches. The moral here is: in the event of a flat-spot, you will save money in the long run by replacing both tires.
Carry a Built-Up Spare
Back to the above example: If you replace both tires after flat-spotting the outboard tire, what happens to that inboard tire with 25% tread remaining? Your shop will dispose of it, you can sell it to a retread shop, or even better, keep it as a spare for an emergency. Buy an overhauled wheel assembly outright and have that partially worn tire mounted. You will have a built-up spare wheel and tire ready to go if the need arises.
Everyone who flies into remote areas, uses strips that are less than pristine or visits airports without maintenance on-site, should give this idea some serious thought. This would work for any King Air. Ignore the complaints about how much space that grimy wheel takes or how much weight it adds. As soon as you blow a tire in the middle of nowhere, the naysayers will be singing a different tune and you will have saved the day.
Note: This is an updated version of the article of the same name from March/April 2011.