Read the opinion of a few mechanics who wrote in about the difference between tube and tubeless motorcycle tires, their use on dirtbikes, and more.
Comstar tires
Q: It has become apparent that I really stepped in it when answering the question about tubeless tires and Comstar wheels. Several readers wrote in to correct my mistake and I thank you all. Here’s a couple of the responses, all of them correct. — Keith
A: In the July/August 2022 issue Rick wrote in asking if he could mount tubeless tires to his 1979 Honda Goldwing. The correct answer is NO NO NO! If the wheel is not stamped TL or Tubeless Tire Applicable, do NOT mount the tire without a tube. The wheel may or may not hold air, but the big issue is that the bead area has to be designed to lock the bead in place. Tubeless rims have a wide flat bead area with a raised ridge on the inside. Without this the bead may separate from the rim under cornering loads. If tire pressure is low, either from neglect or puncture, the tire bead can separate from the rim. The end result is a nasty crash.
Rick also mentioned that the tire would run cooler. He’s right, but who cares? A properly inflated tubed tire will not run so much cooler that the tire life will be significantly enhanced. Unless he’s racing at Daytona he’ll never notice the difference.
As for ease of repair: You get a flat tire with a tube, you throw another tube in it. Only a couple of manufacturers endorse repairing a tubeless tire. The specified repair consists of dismounting the tire and installing a cone shaped plug with a flat patch from the inside and vulcanizing it. This is reasonably effective if the hole is in the center third of the tread. If the hole is in the outer two thirds tire flex will cause the repair to fail. It’s not a matter of IF, it’s a matter of WHEN. Even a center third repair will usually damage the cords. The cords will then cut the plug and it will pop out.
With an external plug such as are used on cars the cords are always damaged from plug insertion, the tire will always fail. Again this a matter of when, not if. These types of repair are only for emergency use until you get to a place where you can replace the tire.
With a bias ply tubeless tire you have the option of installing a tube when you get a flat, but if you plug it, the tire must be replaced due to potential cord damage, and because the act of inserting the plug widens the hole to the point that there is no way to keep out water or road debris.
FYI, most tires now days are tubeless. On a tube type rim you run a tube. Tubes are perfectly compatible with bias ply tubeless tires (not radials). You simply lower the speed rating and the load rating one notch. This means that instead of being rated for a sustained 130mph, you now are restricted to 112mph. Knock 50 pounds off the load capacity. Again, if you are not racing at Daytona, who cares?
I’ve had many customers pull these kind of shenanigans. It seldom turned out well for them, but they keep my shop in repair work. I’m sorry if I sound strident, but this is an extremely serious safety concern. Thanks.
— Vince/Vince’s Motorcycle Store,
Lacey, Washington
The difference between tube and tubeless motorcycle tires
Q: Keith, isn’t the critical point the rim lip profile? Tube vs. tubeless, the rims are shaped differently as are the two types of tire beads.
Tim/via email
A: Here we get to the correct answer I missed in the original question. The inner profile of the rim is shaped differently and is obvious when you look at it. The best answer is check with your local motorcycle tire person and also to look at the rims. Some of the early Comstars are marked TL for tubeless, but nothing beats seeing it for yourself. — Keith
Squeaking disc brakes
Q: Hi Keith, I always read your column first. I love learning how to fix things myself. That said, I put new brakes front and rear on my 1973 Kawasaki Z1. This is the first time replacing the brakes since I bought the bike new in 1973. It currently is closing in on 50,000 miles. Following the instructions, all went well. The brakes work fine and the the disc is in good shape. I changed the brake fluid, and used a sealer on the pads before installing. The problem is the front brake squeaks very loud on occasion. Because it doesn’t happen all the time it’s a bit of a shock when it does. It will also squeak just pushing it around the garage with slight pressure on the grip. Any advice on how to fix this would be greatly appreciated.
— James Lynch/via email
A: There are a few things I can think of that can make a disc brake squeal, pad material and vibration being among them. I’m sure pad composition has changed (for the better) since 1973. A harder pad material would be the likely culprit there. The other thing would be vibration, and you saying it squeals just pushing it around the garage makes that the stronger possibility. Auto parts stores sell a compound to smear on the backs of the pads to help stop the vibration. Is that the sealer you mention? Some disc setups also have springs built into the backing pads to keep the pads in contact with the disc to stop vibration.
Email questions and feedback to keithsgarage@motorcycleclassics.com
