tire/wheel compatability..
 

I tried fixing a flat today, and the tube popped moments after I brought the PSI up to 100. I acquired this bike by trading another for it, and I haven't modified anything. The following is what was already on it:

26 inch wheel

27.25 sized tire

700x25c tube



I was told when I acquired the bike that it was a 27 inch wheel, so I bought a 27 inch tube, and tried to put it on, but the tube was way too big for the wheel. It had too much slack. So I took my 700x23c out of my road bike, that one fit a lot better, but like I said, popped immediately after I pumped it up. I also measured the wheel to confirm it's 26 inch size.

So what I'm thinking is I should get a 700x25c tire, with a matching tube, and replace the existing 27.25 inch tire? I would apprieciate any imput.

You are going to have to clarify where these numbers are coming from.

I assume that your 27.25 is actually 27 x 1 1/4 as written on the sidewall?

If any of these numbers are coming from a measuring tape, you need to throw them out and start again with numbers that are stamped on the rim itself (preferably) or the tire sidewall (assuming the tire does fit the rim correctly)

If the tire is a 27 x 1 1/4 then you should use a 700x18-23 tube.

Before installing, check that all spoke nipples are covered with rim tape.

Before installing check the tire for any nails or anyhting embedded.

Before installing, check for any visible holes in the tire including the sidewall

If all is ok, install the tire: WHen you install the tube, inflate it just slightly to hold its shape and put it in the tire, then put the tire on the rim one bead at a time.

Before you inflate, make sure the beads are both fully installed onto the rim. Inflate slightly and then spin the wheel to make sure the tire is not bumping out at any spot - this indicated that the bead is not seated correctly.

Slowly bring up to pressure and you should be OK

What bike make and model is it?
If the wheel is indeed 26", then you need a 26"/559 tire.

It's a 1991 Raleigh Technium Road Bike...

How did the tube "pop"? Did it break while fully inside the tire or did it push some of the tire bead off of the rim and break when it was not fully supported? If the later, then you didn't seat the tire and tube properly and probably had some of the tube pinched between the tire bead and the rim.

In that case its very unlikely to use a 26" wheel.
for a -91, its unlikely that it came with a 27x-something" originally too(although not impossible) and usually close enough to fit.

Regardless, tubes are quite forgiving when it comes to sizes, but not quite so regarding installation. If you get a fold caught somewhere it can easily pop during inflation. Or, as already suggested, rim strip/old debris issues.

What l_l wrote. Isn't there some difference between a 27" tire marked decimally and one marked in fractions?

Brad

I think that's an option for 26" and for 28", but 27" seems to be limited to one interpretation - 630 mm BSD

I don't think I've ever seen a 27 x 1 1/4" tire marked any way except as a fraction. I've been working on bikes for 30 years, so maybe an oddball escaped my notice...