27" is just your wheel size also known as a 630iso, don't confuse it with 27.5 which is the same as 650b, from there 7/8-1 3/8 will fit, 1 1/4 will be a nice comfortable tire. Its hard for me to tell from your pic but it looks like your rim lacks a bead seat or lip that the tire can catch on, if you have any kind of modern bike you can see what this is, if the rim lacks it don't inflate over 65-70psi; some modern carbon rims are ditching this lip but are constructed to much higher standards to make sure the tire stays on and the tubeless tires that go on them are built to a higher standard. This won't be true of the rim nor of the tires that fit it. The tire remains can also be sharp, make sure you clean the rim well or anything left behind can cut your tube, acetone will help.
Originally Posted by
repechage
The spokes, or lack of the spokes filling the nipples are of concern, that appears to be the front wheel...
Really wide range of take up of the spokes into the nipples.
While you have the tire off, a good time to true or have the wheel trued.
Check the spoke tension too... unless a spoke or two got replaced with a too short one... the spokes when of the correct length fill the nipple at least to the bottom of the slot
Otherwise the weak brass nipple is doing all the work
As long as you don't have more then 1-2 threads exposed you're fine, the spokes don't need to make it all the way through and the nipple is more then strong enough to hold up.
Yeah, time for:
cloth rim strips
new tubes and a new spare
new tires (the Paselas mentioned have a good reputation).
This is a single wall rim with exposed nipples, don't do cloth rim strips, they won't properly stay if you have any form of struggle getting the tire on. Vinyl strips would be fine though I've not found them in this size. Rubber will be perfectly fine for this wheel, tire pressure isn't trying to push through a valve hole, instead the strip is just padding against the nipples.