maiello

Need a bit of advice. I have a Raleigh Banana (standard shop issue) with 700cc wheels. I've been using Continental Ultra Sport 700 x 23c, no problem with them at all. I wanted to change my tyres to the Schwalbe Ultremo 700 x 23c, which I did. Initially I had problems, in the tyre would come away from the rim and the inner tube expand alarmingly. After a couple of re-attempts I manage to get the tyre to stay on and it semed to settle in.

This morning I went for a 25 mile cycle, roads weren't to bad, nothing I'd not been over before. Got home, all seemed fine. Then an hour later I heard a bang. Went to check, the tyre was off the rim and the inner tube had exploded. Absoultley no problems at all while the bike was being riden, or when I paused to have a coffee whilst out.

I'm thinking it could be one of two things: perhaps my rims (chromes from the 80's) are too old for the tyre or the Schwalbe having come folded and the continental's fully expanded and more rigid are just to flexible for my wheels. Would appreciate some advice on this. Is it worth trying the Schwalbe again. I don't really want to change the wheels as the chrome looks great, perhaps over the years the rims have taken a battering, I don't know. The problem only occured on the rear tyre.

Look foward to hearing from folks.

CACycling

I'm guessing your chrome rims are hookless. They will not hold a tire as well as the hooked rims that are standard nowadays. Most have trouble running even 100 PSI on hookless rims especially with folding tires. What PSI were you running the tires at?

FBinNY 

+1, while no one seems to want to address this, there's a difference between straight side and hook edge rims and tires.

With classic steel bead tires it rarely makes a difference, because the steel bead is substantial and keeps a properly seated tires from expanding and blowing off (this is how car and MC tires work).

But flexible bead tires are different. They are not as resistant to bead stretch when inflated and depend being pressed under the hook for added support. Some tire's bead areas even have a bit of a ridge molded in to increase the latching effect. These often will not do as well on straight side tires, and in any case need to be seated very precisely, and checked at intermediate pressure.

Note that not all steel bead tires are immune to the problem. In an effort to save weight many have thinner bead wires and so are not as rigid as their heavier counterparts.

Lastly, it's common for tires to blow off even if everything is right. When mounting it's easy to trap some tube under the bead, which as you inflate lifts that part of the tire higher setting up a future blowout. After mounting, inflate to 10-20psi and check for uniform seating, and any section that seems to be away from the rim. This ius easily done by spinning the wheel and watching for twists and wiggles, then watching the molded lines near the rim for rise and fall.

maiello

Yep, hookless. I was running the tyres at 110psi. Oh well, I'll have to invest in a new set of continentals.

maiello

Thanks for that FBinNY, very helpful advice. As I just mentioned to the other chap I think I'll reinvest in the Continentals. In truth I've had no problem with them, I was just beginning to pick up punctures more frequently, so I thought they might need a change.

FBinNY 

Since you already own these tires, why not give them a second chance, being very careful about seating. Odds are they'll be OK at reasonable pressure, like 90-95psi, and there's little or no benefit to going above that anyway. IMO anyone riding at above 100psi is probably better off with a slightly larger section tire.

CACycling

I used Forte GT2/K tires on my old Schwinns with chrome, hookless rims and had no problem running them at 100 PSI. 110 PSI would blow them off the rims pretty consistently. As noted above, you need a non-folding steel bead plus you need to be very careful to make sure the tire is seated properly before inflating fully and keep the pressure at 100 PSI or less.

Mauriceloridans

Until I bought Schwalbe, I didn't know the max pressure rating on a tire was for hooked bead rims only. It is common knowledge you need wire bead tires for hookless rims but I had not heard that you must use lower inflation pressure. Schwalbe says this on the cardboard that stapled on the new tire.