BDurant

With all the different methods of indicating tire sizes and rim sizes not to mention tube sizes as well. Is there a method of sizing a rim and tire to match correctly? Maybe the circumference of the rim vs. the inside circumference of the tire itself?

For instance after replacing the inner tube I can usually pinch (using my fingers) the tire so that it’s back onto the rim starting at the stem and work my way around until I reach about 8 to 10 inches from where I started. Then I need to use a wrench to finish the last small section.

The reason I ask is that I have a rim that says it’s a 28” and a tire that says that it too is 28” but I don’t think they fit the way they should. On this rim/tire I have now, I can pinch all the way around without the need for a wrench. After filling the tire to 5 lbs below the recommended pressure and some short riding on flat ground the tube squirts out the side of the tire and rim thus exploding. Hum???

10 Wheels

Back up: What bike is it? What is the brand of the rim?

AEO

https://www.sheldonbrown.com/tire-sizing.html

what is the 28" followed by? fraction? decimal?

BDurant

Thanks for the response.

- The bike is labeled Mongoose
- Stamped on the rim is the following: (-) HJC P-6Nx700c
- Stamped on the axle housing is the following: Dachang
- On the side of the tire is the following: (47 – 622) 28 x 1.75/700 x 45c E–507-01

10 Wheels

Looks if as your NOT getting the tube all the way past the tire bead when you install the tire.
It takes some practice.

AEO

this is more common on fatter tires than narrow ones. inflate partially (under 10psi) or just enough so you can move the tire around on the rim, and make sure the tire bead is sitting properly on the rim. inflate to higher pressure, and check to ensure that the bead is still sitting on the rim properly. after that, inflate to optimum pressure, for 47mm wide tires that can be anywhere from 40~60psi and check your work before riding it.

BDurant

I looked up the Sheldon Brown’s website (one of your suggestions) and followed the info there and measured the rim. Here’s the measurements: BSD = 614mm and the Inner Rim Width = 21mm. Now, from what I see the BSD is the Bead Set Diameter. With the tire laying on the ground (not on the rim) I carefully measured the ID of the tire in six locations on each side and took an average= 620mm

Jeff Wills

There's no good way to measure the tire- it's too flexible. However, since a 700C tire has a bead seat diameter of 622mm, you got pretty close.

How did you measure the rim? It's a 700C rim (that's what the stamp says), so its diameter should be 622mm or very close.

Short answer: that tire should fit on that rim. If the tire blew out, then the tire is damaged somehow or it wasn't seated correctly to begin with.

Kimmo

...Or it's just a particularly cheap and nasty tyre.

Many of the cheaper tyres are simply awful.

BDurant

Thanks for the response.

630mm = Rim total dia.
614mm = Rim’s Bead Set dia.
622mm = Tire ID

So you’re saying that this tire and rim match?

operator

There's no such thing as a 614 bsd tyre. From the markings on the rim and what is generally expected of a walmart type "mongoose" bike, it will be 700c or 26", that is 559 26", so Jeff is right in post #8 - the tyre is compatible with the wheel. However, the symptoms of your problem suggest that it is either

a) slightly larger than usual bead set diameter (not unusual for crappy tyres - bad quality control)
b) rim is slightly undersized

Could be a combo of both, or the tyre is actually a 27"/630 tyre on a 700c rim that is mismarked.

Jeff Wills

Earlier you posted:

- Stamped on the rim is the following: (-) HJC P-6Nx700c
- Stamped on the axle housing is the following: Dachang
- On the side of the tire is the following: (47 – 622) 28 x 1.75/700 x 45c E–507-01

Note that both tire and rim are marked "700C". They match.