Tire Trouble

[wrongway]

A couple years ago I bought a Schwinn (possibly WWII era) 26x1-1/4 wheel set with a 3 speed hub. I am using these on my '34 RRA replica. I had a new set of 26x1-1/4 tires that I bought by mistake at one time. For some reason I've always struggled with these tires/tubes/wheels. I've had two tubes blow out on the rear. That may or may not have been a slightly exposed spoke nipple. Last night I was riding this around town some; not far and since I only had around 33# of pressure I aired the tires up to near 60# (the tires call for a maximum of 70#). I didn't get across the street when I heard a 'whisp-whisp' sound. I looked down to find the front tire bulging as the tube was making an escape! I stopped, let a little air out (added more back via frame pump) and continued on. Not 30 seconds later the rear did the same thing.
Sorry this is long, but I thought I should explain it. What is going on? I would guess that the tires are too big around and thus not seating the bead on the rim. What size should I have on there?

 

[bulldog1935]

your bead is stretching. Probably time for new tires.
I had the same problem running Challenge clinchers on my road bikes. Kevlar bead instead of wire, but they stretch and eventually give up.

 

[wrongway]

They are new tires, or so I would assume. No cracks. Soft enough. I have to use tire tools to put them on. Maybe I could try new tires. Since these are Schwinn wheels from the 40's what tire size do I need?

 

[bulldog1935]

I see. It's still the same problem, just not age related. You're essentially getting a pinch flat, but it's because the bead seat is not getting a good bite.
I'm assuming your rims are not hooked, and your tire bead is wire.
I go through an algorithm installing tires to eliminate all pinch flats. Start with a little air in the tube.
Always begin the bead next to the stem and work your way around in one direction. When you get back to the stem, let some air out and push inward on the stem to seat the final piece of bead. I then air it up to 20 psi, then let some of that back down, so I can push the tire bead inward and see the rim strip. I go all the way around the tire making sure I can't see tube. Then air to final pressure.

 

[wrongway]

Thanks. I'll try that method the next time I'm less frustrated with this bike!

 

[momo608]

What was the called for tire air pressure for these rims from the factory? just because the tire is rated for high pressure it doesn't mean the rim is. It could also be that the repro tires are junk.

 

[rhenning]

War or prewar Schwinn lightweights used 599 bead seat diameter wheels/tires. After the war they went to the more common 597 bead seat diameter wheels/tires. That means the tires you are using a 2mm smaller than the wheels you are using. That makes them very hard to install and in the long term the beads will break. Non compatable parts. Roger

 

[wrongway]

I'm thinking the same thing. It makes a nice museum piece, but it's unsafe and un-rideable as is. I only think that these wheels are this old due to the fact that the Sturmey Archer hub has no date and both ends of the hub are black.

 

[wrongway]

I wondered about the rim pressure, too.

 

[bulldog1935]

for a 32mm tire, 60 -65 psi should definitely not be excessive, and should be just about right in the rear.
Here's the Berto chart for starting tire pressure v. wheel weight load

Good soft tires will run well a little bit below this, and harder tires may need higher.