El Gato27

All,

A friend at work asked me to check his old schwinn. He has mixed parts on it so not original wheels. He said the tires kept blowing out. He is using 26x2.0", but they look pretty dried out. Tubes are 26X1.5/2.2.
I measured the inside rim width and it measured 24.4mm. This is where I need a double check. I am following Sheldon Brown's guideline of 1.45-2.00 X inner rim width.
So my range is 35.38 to 48.8mm tire width. Converting to inches my range is 1.39" to 1.92". So is my math correct? And I should replace with tires thinner than 2.0"?
Thank you.

Felix

Unca_Sam

You don't need to. When you replace the tires put in new rim tape. Unless the tire sidewall ripped or his bead is blowing off, he is probably having the tube push out a spoke hole.

Your math isn't wrong. 26" 559 bsd tires are denominated in inches, so a 1" inner rim width will let you run 1 1/2 to 2 inch tires. Frame clearance will likely limit anything larger.

El Gato27

The rim tape looks good, no spokes poking through.

Unca_Sam

The rim tape needs to resist the inner tube. If the Tube has holes along the inside, the tape is no longer strong enough to prevent the tube from pushing through.

My wife's 1980's Fuji had an issue like that, and replacing the rim tape and the tube stopped the problem.

dabac

I’m not sure what you mean by ”tires blowing out”.
but there are no less than five different 26” sizes that don’t interchange.
If the tube is herniating between rim and bead, double-check that rim and tire are compatible as a first step.

Bill Kapaun

+1
Blowing out or blowing off?
EXPLAIN what's exactly happening.

If these were 26X1-3/8" tires, I'd say you had a "Schwinn tire" (597mm BSD) on a "non Schwinn rim" (590mm BSD) IF it was a blow OFF.

El Gato27

He said they were blowing out often. I'm thinking the tire was not holding the tube. The tires are not damaged, the bead does look old.

Bill Kapaun

So we're supposed to guess what's actually happening?
What a waste of time.

Unca_Sam

the tires will list the ERTRO size. The big number is the bead seat diameter (bsd). With the tire of off the wheel, use a string to measure circumference, then divide by pi to find diameter. Measure the distance from the bead hook to the place you measured the circumference, multiply by two and add to the diameter. Pick the sizing standard closest to that number. Is it a match for the bsd on the tire wall?

Unca_Sam

It's interesting that you wasted your time to even comment. 🤔

Are you cranky today? Maybe you'll feel better after a beer and a nap.

Bill Kapaun

And your reason for your comment?
What a ......
Another to the ignore list.

Unca_Sam

That's the crankiest snowflake I've ever encountered.

El Gato27

Unca Sam, thanks for checking my math. I'm going to try some 26x1.75" tires I just picked up.