Jim’s Tech Talk
By Jim Langley
Whenever Tech Talk is about tires, like the last episode, we get great comments. This week, I want to answer readers “William” and “Mic,” who had questions after reading last week’s tire seating tips.
William asked “I don’t understand the low spot on the tire concept as in find the low spot(s) on the tire. Could you clarify please?”
To help William, I took another photo. This time I used a tiny wheel in the hopes that it’ll show more of the tire so it’s easier to see the low spot. On the left of the photo I placed a single arrow pointing at the word “INFLATE” on the tire. I placed two arrows pointing at the bead seat line molded in the tire.
To find or see a low spot in a tire, a spot that’s not seated, you look carefully at both sides of tires and all around both sides. It helps to have good lighting because what you’re looking at, while they’re molded into the tire, are not always easy to see or evaluate.
For the photo, I chose one with a pretty good impression so that you can see it. Look closely at the text on the tire that says “INFLATE TO 70 P.S.I. (ON-ROAD 70 P.S.I. & OFF-ROAD.
The arrow on the photo points at the word INFLATE. Notice that the bottom of the entire word is not showing because it’s hidden beneath the rim still. Now gradually read the rest of the text and look at how the words rise up and out of the rim.
When you get to the two other arrows on the right they are pointing at the bead seat line. That line exists on almost all tires and it’s the indicator of whether a tire is fully seated or not. In this case, the line is clearly visible on the right but over on the left it’s hidden with the text below the rim. That’s how you find a low spot and realize that part of the tire needs to be seated. The bead seat line should be visible all around on both sides of the tire when it’s fully seated.
Sometimes you can use another technique, which is to spin the wheel and look down onto the tread on top of the tire. If the tread runs straight down the center as the wheel spins, it’s likely the tire is seated. But, if the tread wobbles, it could be a sign that it’s not. But you can’t be sure because tire treads can wobble for other reasons, too. Which is why knowing how to look for the bead seat line is the more surefire way to check the tire seating.
Mic asked “How can you tell if it’s a bad tire or a bad rim, not because you are doing it wrong? When is it time to try a new tire, or different type?”
I’m not sure if Mic is asking about tire seating or tire installation. Assuming it’s seating, usually it’s not the fault of the tire or rim, but just something that happens with new tires, because they can be a little stiff and tight. I gave some good tips in last week’s column and readers added more, Mic, so if it’s tire seating that’s going wrong, those should help you seat whatever tires you have.
If you’re asking about bad equipment, tires and rims, causing tire installation issues, that’s always a possibility today. Because there are tires today that are undersize and rims that are oversize and that combination can make installation difficult, even nearly impossible. If you want to read a tire installation horror story, see the next to last comment by “Fred” in last week’s Tech Talk.
In my opinion, the time to try a new or different type tire is the first time you try to put that new tire on your wheel. If you have been able to install tires before and you can’t get the new tire on and you’re sure your technique isn’t at fault, I would put the tire back in the box and return it for another (assuming you purchased it from a shop that accepts returns, which they should for new tires).
Depending on where you buy your tires, you might also be able to discuss with them before buying which tires they can assure you are installable by hand.
Getting a proper fitting tire is much better than forcing the tire on and then not being able to fix a flat out on the road. Even if you have to try a few tires before you find the right one.
What’s your take?
Readers, please weigh in if you have more tips for William and Mic. And thank you for the excellent comments!
Jim Langley is RBR’s Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his “cycling aficionado” website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim’s cycling streak ended in February 2022 with a total of 10,269 consecutive daily rides (28 years, 1 month and 11 days of never missing a ride). Click to read Jim’s full bio.
Thanks Jim. I knew this was a thing on my (tubed) tires when inflating but I didn’t know the official name.
My next bike will have tubeless, and I appreciate you taking the mystery out of it for us. Especially for inflating the tire, and “why won’t the tire bead seat so I can inflate the tire?” is the question I hear about the most.
I’ve been reading you since decades, and I always learn something new and useful I’ll share my favourite tip (I probably learned from you): when when inflating a tire with a presta valve, before putting the pumphead onto the presta valve, I put a bit of saliva into the pump head valve-hole to let it slide more easily on (and more importantly: off) the valve before and after pumping. I find a lot of pumps are hard to get off the valve, and the presta valve is a fragile little thing.
Happy to help, William, and thanks a lot for sharing that tip. I have given that tip before but like most tips, it was passed on to me years ago by my cycling mentors so I can’t take credit for coming up with it.
Thank you!
Jim
Good topic and explanation Jim.
On our last trip, I rode my new camping bike and it had a disconcerting shimmy as we went down the road, especially when riding a little faster and on pavement. I was initially concerned that the rim was out of true, but when I returned to camp, spun the wheel and the rim felt true, but the top of the tread didn’t ride true as it spun. I then searched the edge of the tire on both sides and found that the tire wasn’t seated properly. Tire re-seated and now it rides great!
Thanks a lot for sharing the story about the shimmy, Harold, that’s a great reason to make sure tires are fully and properly seated. I’m glad you found the problem and seated the tire, good job!
Thanks again!
Jim