G4teamG

Just changed the tires on my bike to Specialized Nimbus Armadillos. These tires are fast but I seem to have a problem that I just can't seem to fix. The tube keeps getting pinched by the rim. I have added a second rubber tire liner, and cloth tire liner but the problem persists. The side wall reads a maximum inflation of 100 psi. I will replace the tube (was using Kenda tubes) with a Bontrager tube to see what happens. Just can't seem to inflate past 80 psi. Would like to get up to 100 psi, although I do weigh 205. Any suggestions? Thanks for the advice.

allgoo19

https://www.bikeforums.net/bicycle-mechanics/90011-s-final-100psi-isn-t-enough.html

Check this thread, scroll down, you'll find the chart. It shows how much to inflate your tire depends on tire size and your weight plus bicycle. Personally I think the chart runs too low by 20 psi.

What you use to inflate the tire and not getting it past 80 psi? If you are using general purpose air pump, try floor pump made for higher pressure. You can get it like $15.-. They inflate tires beyond 120psi easily.

Also, you may want to invest in pressure guage you can find in bike catalog or bike shop. The one you can find at hardware store is not good for highpressure. Even if the pump has a guage, having separate guage is still valuable because the guage on the pump goes up and down and hard to see which one is real pressure.

doctorSpoc

could be any number of reasons:

1) maybe the tube is too big for the tire and is getting pinched as you are trying to stuff it in there... may need skinnier tubes
2) are you putting a little bit of air in the tube as you are putting the second tire bead on the rim? if you don't do this sometimes the tube gets pinched.
3) carefully inspect the tire for a peice of glass or debris that could be stuck in it
4) carefullty clean the inside of the rim to make sure there is no debris insdside that could be causing the flat
5) before you fill the tube go from the valve all the way around the tire... squeeze the tire so you can see if any part of the tube is poking out... if it is it will get pinched by the tire bead. sqeezing usually make the tube go back where it should be, but you will need to have a little air in the tube for it to behave itself
6) also before fill your tire push the valve in and then pull it out to make sure the tire bead isn't pinching the hard area of the tube around the valve.

That's my regime that I go though to make sure my tires go on with no pinched tubes

supcom

Where is the tube getting punctured? Is it on the spoke side, tire side, or sidewall side?

Do you have a singlewall, deep profile rim?

G4teamG

The tire is getting pinched on the area that faces the rim. If I inflate the tire to 80 psi there is no problems but as soon as I go to 90 or above the tube will pop. The area that has popped usually is around the area that has the raised ridge on it, or in other words, the area where it looks like there are two pieces of rubber coming together to form the tube. I have been told that sometimes electricians tape (or maybe even a thick piece of cloth tape will fix this problem but I already have a cloth rim strip on it). Thanks for the pointers guys.

Raiyn

Might also want to check your rim tape. If you still have the rubber or cheap plastic stuff switch to a cloth tape like Velox or Zefal
Define "liner" it sounds like you got 10 pounds worth of stuff in a five pound sack.

G4teamG

The cloth rim tape is brand new, I bought to go along with the Specialized Nimbus Tires. Those tires are awesome. My only problem is taking advantage of the higher psi that seems to keep blowing out my tubes. This is frustrating. I feel like there is some hidden speed in those tires I just can't seem to take advantage of.

pnj

this is on a road bike, correct?

when you put your tires on, put them on the same way each time. if there is a logo on the tire, put that right next to the valve stem. this will help you figure out where the tube is getting a hole in relation to where it sits on the rim.

then you can check the rim/rimstrip in that location and see if you find what the issue is.

do they blow out while inflating or while you are riding? are you using the correct tube size? what brand tube are you using?

Retro Grouch 

OK, try this: Armadillos have their place but they aren't the easiest tires in the world to install because they have such super stiff sidewalls. Most likely you are getting a tiny bit of tube pinched under the sidewall which causes it to blow off as you get it up to pressure. Some of these tricks might seem to be counter-intuitive, but stick with it and it'll work.

1. If you have more than one layer of rim strip, get rid of the extras. Too much bulk is going to make the tire more difficult to install.
2. Make sure that your tube matches the size of the tire. If your tube is a little undersize, that's OK. If it's even a little bit too big, that's bad.
3. Put about 1/2 psi or air into your tube. Just enough to make it round.
4. Put the tube into the tire while the tire is still completely off of the rim.
5. Rub a bit of talc or baby powder on the outside of both tire beads all of the way around to make it slide onto the rim more easily.
6. Starting at the valve stem, install the first bead all of the way around.
7. Starting opposite the valve stem, start to install the second bead. Work evenly in both directions. You'd like to end at the valve stem.
8. As you get near the end the last bit of bead will be hard to install. If necessary, deflate the little bit of air in your inner tube. Try to pinch the tire beads together opposite the valve stem and work all of the slack up to the last bit of bead. Avoid using tire levers if you can.
9. After the last bit of bead finally pops into place, push it away from the rim so that you can peek inside to be sure the tube isn't pinched under the tire bead.
10. Inflate the tire to about 30psi and carefully inspect the bead all of the way around on both sides. If the tire doesn't look the same all the way around, deflate the tire and check for your innertube trapped under the tire bead again.

supcom

I have a folding bike that suffered this same situation. The rim was a single wall deep vee. When the tire was inflated using a narrow tube, most of the tube would expand to conform to the tire. As pressure increased, the small section of tube facing the rim would then expand into the deep vee of the rim. The tube would eventually be stretched by the pressure so far that it would split. Coincidentally, the magic pressure was about 90 psi.

The solution in my case was to use an oversize tube. The tires were 20x1.35. I ended up using 20x1.75 tubes. The extra tube material can then expand into the rim with less stretching. I've had no problems since then.

Since Nimbus tires are pretty narrow, check your rims. If they are single wall, and especially if they are deep profile, try using a larger diameter tube. They're a bit trickier to install in the smaller tire, but they might solve your problem.

Of course, I assume you have gone over the rims carefully to make sure there are no burrs or other sharp edges.

Avalanche325

Here are a couple general things. Lots of good ones have been mentioned.

Talc the inside of the tire. Also talc the tube. This will let them slide against each other instead of grabbing.

See if you can determine if the blowout is in the same place. If so, that will guide you to the problem. It could be a spoke sticking through (it dosen't take much), or a burr on the rim. You fingers will tell you this better than your eyes.

I had a wheel that I kept getting flats on. Finally, out of frustration, I took off the rim tape that I always used, and put on the harder rim strip (like came with the rim....hmmm). It fixed it.

G4teamG

This is a mtb that I want to use as a commuter. The original tire size was 26x2.1 (WTB Raptors). Originally, the wheels had a single rim strip made of rubber. I added a second strip of rubber over the existing rim strip. On Sat, I aired up to 90 psi and rode for about 32 miles. Did not have any problems. On Sunday at 6:00 am, the rear tire was flat. So I added a cloth rim strip I purchased at the lbs. Sunday night as I was cleaning my bike the rear tire flattened while the bike was upside down. The tires were aired up to 100 psi before I started cleaning. Today I went riding at 80 psi with no problems. The original tubes were made by Kenda (1.5-1.75). The new tubes are from Bontrager 26x1.25-1.75. The lbs said to put the original 2.1 mtb tubes in and see what happens. Should I?

supcom

Give the 2.1's a try. You could also try some wally world 'universal' 26-inch tubes. they may be a bit smaller than the 2.1's.

Raiyn

Both of these were mistakes. Use only ONE rim tape per whee, preferably cloth. I also suggest using the 1.25-1.5" tubes then follow Retro Grouch's advice except for step #7 start AT the valve stem not opposite it. Opposite is for removing the tire

Avalanche325

I know there are several different "raptors" in the WTB line.

Aren't WTB Velociraptors and others, only rated for 75lbs????

Noah Scape

Simple... get bigger tires.

G4teamG

The Raptors were for mountain biking. I bought the Specialized for the commute. When I ran the raptors they were aired up to about 60psi. The Specialized are at 80 psi. Sorry for the confusion.

G4teamG

Noah, I'm currently trying to lose the spare tire. I started at 230, now I'm 205. I'm trying bro, I'm trying!

Retro Grouch 

I disagree strongly. The object is to get as much slack in the tire as possible to make it easier to force the last bit of bead onto the rim. To do that, you'd like to force the opposite side of the tire as far into the center of the rim as you can. The thickest part of the innertube is where the valve stem is attached. If you start installing your last bead at the valve stem, you are minimizing the amount of slack you cen generate in the tire.

Noah Scape

Listen… no offense meant. I'm 220 and I wouldn't ride anything less than a 32. I don't know what size tire you're ridin, but if it is smaller than a 28, I'd say give a 28 or a 32 a try and see what you think. If you don't agree life is better I can't give you your money back on the tires, but I would be very surprised.

sakarias

Not meaning to get into the middle of an argument, and maybe MB tires are different than high pressure road tires (if so, ignore this), but I always mount one bead of the tire first, at the valve hole, push the free bead of the tire toward the opposite side, exposing the valve hole, insert the tube, tuck it into all around, then start mounting the unmounted bead, starting AT the valve when seating the tire. In order to make sure the tire is seating fully, I may have to push the valve stem in toward the tire, somewhat. The result is the tire is seated and the thicker valve area is inside the tire -- not with the tire sort of resting on the tube.

I often use the tire iron to push the tube into the tire, tucking it in so that it does not get pinched as I progress around the rim installing the second bead.

The other thing you can to help the process is squeeze the tire away from the rim, pinching it all around. With the tire edge in the "valley" where the spoke heads are, you have it in the place of smallest rim circumference.

Hope I'm being clear. Like I said, I may be misunderstanding the discussion. If so, feel free to ignore this.

Raiyn

Nope that sums it up nicely. I do this with all tires