No matter if the rims are cheap or not, if they are keeping in one piece and are not deformed, cracked or otherwise damaged, they should be fine. Having another blow off with the same type of the tire, is that the same tire you already had a problem with or is it the other one? This is getting very very worrying, to have them blow just like that.

That is probably a single wall "C" bead hook rim. The "C" denomination means that ih has a "lip" or "hook" under the side walls where tire bead sits. Such rims are specifically designed for inflation pressures of over 5 bar or over 75 PSI. Even a non branded "C" single wall rim should be good for up to at least 6.5 bar or about 97 PSI. So that leaves us the tires as the likely culprit - if you had those tires on standard, non "C" designated rims, and pumped them up to 75 PSI or over, tire might slip off due to the rim, but you had proper rims, and had tires properly inflated, and that keeps pointing towards the tire for me.

As I said earlier, if the tires are rated to 87 PSI as these are, even 100 PSI should not blow them off the rim if they are good. Real blow off pressures are much higher then the rating that the tire has written on the sidewall, typically up to twice that pressure is common. I would get concerned to tire blowing off the rim (having quality rims in mind) no sooner then at least 130 PSI in them. And they probably wouldn't blow under 150 PSI if everything is ok. I'm not saying it is ok to ride like that, just giving you a scale of pressure needed to blow the tire off when everything is working as it should be.

If you were pumping them up to full rated 87 PSI, that is nowhere near enough pressure to blow them if everything is ok and if the rim/tire combo isn't defective. Even if you pump was off by as much as 20%, that would still only give 105 PSI, nowhere near enough pressure to cause this. Something is clearly defective here, and until that is found out and repaired I would not dare ride it like it is.

Sorry, but at this stage, having two consecutive blow offs with those tires; it is not about luck anymore, it is about the question when will it happen again, not will it happen, but when. Take a look again at what I said about pressures, there is something SERIOUSLY wrong with either the rims or the tires if you need to run under inflated tires in hopes of it not happening again. And remember how it was when it happened at 20 kph, so think again for the sake of your safety - what would happen if the tire gives out again at a higher speed, and if you happen to go down in traffic around heavier vehicles? I don't need to answer that one, do I? Please, rethink you decision and remember that this is not a game - sometimes, we can loose sight of what is a reasonable risk to take, and what is not.

Seriously, in my opinion this had crossed the line of unreasonably dangerous defect to ride on, so please do the prudent thing, and bin those tires before you get seriously hurt. Or the rims. Whatever is causing the problem, find out, bin it and replace. A few dollars is not worth your head or your health, trust me. I really wouldn't like to read about another fellow rider getting hurt over a defective part.

And, good suggestion there with the Schwalbe, got me thinking - they have a new Marathon Green in lineup for 2011? I might give it a try, didn't really like the feel of old Marathon Plus, but this new Green looks like a solid balance between weight of the tire, puncture protection, and price. Redesigned sidewall might mean a better feeling ride. I found Marathon Plus too heavy and sluggish, and plain Marathon not enough puncture resistant, so this new Green seems like a good compromise between both, might just work. But what I did love about Schwalbe tires, was always theirs uncompromising quality, that's true. And, I've never had any of their tires blow off while riding or at any time. Interesting food for thought, and a very good video there.

Thanks for your detailed feedback and obvious concern, whitecat. I'm not ready to give up on the tires just yet; as I said I had about 2000 incident-free kms on the set before the blowouts. It's not a monetary thing (you can't put a price on safety) - I just think it was an anomaly and that they are still excellent tires. In any case I installed a new tube in the rear last night and set the pressure at 65 psi rear, and 55 psi front. I rode the bike to and from work today (it was a short day) and the tires held just fine. I will continue to keep my speeds low and avoid busy streets for now. This bike will soon be retired for the season and hopefully next year I will be able to upgrade the wheels. I don't think, however, I will be recommending the Michelins to anyone in the foreseeable future.

Sounds like the tire was not fully seated into the rim. When you mount the tire, use soapy water. I use a wet paper towel with plenty of dish soap and apply liberally to the tire beads. Your tire and inner tube will dry on its own. Soapy water is particularly helpful when mounting new tires that have not stretched.

Carefully inspect the tire seating as you are inflating (right where the rim meets the visible portion of the tire sidewall). Stop halfway to full inflation and check that both sides of the tire are correctly seated. Continue to max inflation and again closely inspect. If the tire is not perfectly mounted and fully, evenly locked into the rim, start again. Otherwise, you risk a blowout as described, particularly if you run at max inflation.

So get off your soapbox and DO something about it - don't just keep yammering about it on BF. You've convinced yourself that those particular tires are dangerous (and never mind all the posters pointing out that a couple of anecdotes don't really make a trend, that it could have been faulty mounting, etc. etc. ad nauseum) - so what do you propose to actually DO to make the world a safer place? Sue the pants off Michelin? Work with DOT and CPSC to organize a nationwide recall? Write a letter to the Pope expressing your heartfelt belief that pedophile priests should be given bikes with these particular tires, and suggesting that he excommunicate all members of Michelin's board of directors?

You've made your point here - time to move on.

Well, I think it's time for someone to take the bike and go riding, as he seems a bit grumpy
Maybe that will improve his mood

Or, if he has enough free time, he might follow trough on his ideas, if he thinks it will help anything.

Or, he can simply stop reading what he doesn't want to see, because he will fail in his attempt to direct what others think, do or write about.

Take you pick