Ewok

Sorry if this should be in the mechanics section, since part of my questions pertains to my weight I thought it fit here, please move this if I am wrong.

Anywho, my new tires and tubes came today for the mountain bike I've been fixing up to hold my rear end up. To be honest, this is my first time ever changing tires and tubes but I read up a lot and watched different videos on how to do it. I got the wheels off okay, I don't have quick release so I had to unbolt them. I even got the tires and tubes on the wheels and back on the bike fine too.

But, this is where my problems begin. When I try to inflate either tire, when my guage reads 30-40 PSI, the innertube pushes the tire out past the rim of the wheel leaving the tube exposed. It's 26x2.0 slick tires and I know they should fit because the mountain treads I replaced were 26x2.25. And the tubes are also 1.75-2.25. It also feels pretty dang firm at 30-40 and it makes me nervous to even sit on the bike (even if the tire wasn't poking past the rim) for fear of bursting it. The tires are rated for 30-80 psi though.
I'm using a pump that is almost 10 years old though it hasn't been used much, could it be giving me false readings? What could I be doing wrong? How much PSI should I inflate my tires to with me weighing 265?

I'd appreciate the help, I don't really know what I am doing at this point and I don't have a way to get the bike to a LBS. I was really hoping to get biking by friday because it's when my spring break begins Thanks for your time

TrojanHorse

So you replaced the tire as well as the tube? It sounds like either the tire isn't mounted properly (you should never see tube) or you bought the wrong size tire. I'd verify the measurements if I were you.

If the tires are rated to 80, feel free to pump them up near there. I run my road tires right at the limit on the tire.

It's possible your tire pressure gauge is off but I can't imagine it would be THAT off. Do you have a car tire pressure gauge you can use to compare?

Bill Kapaun

When you first start to pressurize the tire, is the bead seated evenly ALL the way around?

Air your tire up to a "safe" amount and take the mounted tire to a tire shop and ask them to verify the pressure.

Ewok

It's quite possible that I am doing something wrong since this is my first time. I wrestled with it for about 2 hours today and stopped for my sanity. I double checked the sizes before posting for the sake of accuracy, so that's not it. I don't have a tire pressure guage handy. I'll try inflating it to 75 and see if it goes. Again, is it supposed to feel extremely firm at only 30 psi?

The bead should be seated along the rim yes? I have been trying to follow the videos I have watched best as I can, but unfortunately there seems to be a serious lack of close-ups to be able to see it fully. I will give it another go tomorrow before tracking down my LBS.

skilsaw

let the air out of the tube until the bead drops down into place. With the tire nearly flat, squeeze and press the tire onto the wheel. Work your way around the tire, squeezing and pressing one hand width at a time until you have been all the way around the tire. When this is done, re-inflate it... and good luck.

DTSCDS

Here's what I do.
Starting with 'half' of the tire on the rim. (half of it is still hanging out in space.) I put just a touch of air in the tube so that it will semi hold its shape and then put it inside the tire. (A little thing that will mean a lot later is put the tire's label at the same location as your valve stem--if you get a flat later you can use it as a reference to check the rim against the hole in the tire looking for sharp/pointy things.)

I like to start putting the other side of the tire on into the rim at the valve stem--that way I'm not fighting it when I get down to the last few inches which are hard enough to seat anyway. Work in opposite directions with your hands, seating the tire inside the rim. (Your hands will move away from each other.) This is where having just a touch of air in the tube helps it hold its shape a bit. BE VERY CAREFUL not to pinch the tube between the tire and rim. Only bad came come from that. This will be especially important, and more difficult, when you get to the last few inches. There is no easy solution for getting the last little bit of tire to pop into place--it's sheer will and determination with some added forearm strength.

Cursing seems to help some here.

Once it is in place go around the rim squeezing the tire, both sides toward the middle. You are looking for places where the tube might be squished between the side of the tire and the rim. After being sure everything is in its proper place I pump it up to 20 pounds or so--just enough to get the pressure up and seat the tire bead. Then, I let the air out completely and re-check to be sure the tube isn't pinched anywhere. Then it's time to do the real inflation.

Yes, even at 30 pounds the tire will feel pretty firm. But, like others have said, you might want to get your pump checked for accuracy. I concur that it would be VERY unusual for it to be off the kind of amounts you are thinking it might be.

CraigB

Thumb pressure can't even begin to compete with fully-loading a tire, so don't gauge pressure with your thumb.

The one thing I always do to make sure the tire's bead is seated properly around the whole wheel is to hold the wheel by the axle or skewer and spin it at a slow-to-moderate speed while looking at it from the front (like the tire is trying to roll over your face) and keep an eye on it for any severe up-and-down action as it rotates. If you get a substantial high spot, there's a good chance the bead isn't seated there properly and may even be pinching the tube.