I bought a set of Bonty Race Lite 2007 with paired bladed spokes. I rode them hard for 2 years. They were bombprood until I got a little hop. Had a good LBS true them and the next ride a spoke completely loosened. The LBS had warrantied a number of of Bontrager rims in the past for cracked hubs, rims, etc. Those issues were supposed to have been fixed by 07. Trek shipped a new set in 2 days.
I rode them last fall for a few days. We moved Down Under this spring. After 3 rides one of the rear spokes loosened up. I took them to the best shop in Adelaide for trueing. Next ride another loose spoke. They were also a Trek dealer, so they offered to warrenty them. TrekAU had to contact TrekUS to get a new set. It took 5 weeks to get a new wheelset.
I got the new set last week. They finally did away with the paired spoke. The added more spokes to the rear. New DDswiss hubs. Very nice wheelset.
I went for my first ride up in the hills. Doing 40 mph down hills, etc. They were fine and stable. Good climbing/descending wheels.
I went for my second ride today. I was doing 15-20 around a 270 degree turn and the rear tire came off the rim. Thank god I used to ride MTB everyday for 5 years. I came so close to tasting the tarmac. Scared the hell out of me.
When changing the tire it became obvious that the rims are under size. Not perfect 700c wheels. I can take the tire off and on with one iron. MTB "style". I was chatting with a cycling friend and took the tire off with one thumb. Front rim is smaller than rear.
I checked using 2 different tires(conti & specialized) on the Bonty's and a Ultegra rim(which requires 3 irons).
If you're more specific in the thread title, you'll find that more people will actually read your post. Also, ask the question up front...then elaborate for those who want additional details.
I mount and unmount tires from both my own and my wife's road bikes without levers every time...and have no problems with blowouts.
On tires that aren't crazy hard to mount (actually with all tires), it's important to check the tire bead all the way around the rim to make sure it's all seated properly during inflation. Even if a tire and rim "fit" properly together, if the bead seat of the tire has collapsed too far into the rim at one or more spots, the tire can be blown off the rim on the opposite side where the tire is has more slack than it should.
The other thing that will cause this type of blowout is having a tube pinched between the tire/rim during installation. At some random point, the tube will blow the tire bead off of the rim.
1993 XO-1, early 1980s witcomb fixed gear, 1993 MB-1 singlespeed, a Surly 1x1 with pugsley front end, trek 520 converted to 650b, Coppi lugged road bike, Schwinn Crisscross townie
I would say the 3 tire lever tire/rim combo is the exception, not the rule. I have mounted countless tires (generally around 5 a day) for 12 years, and within that time have only seen 2 tires that you needed more than one lever to mount/remove.
Anyway, that said, it is remotely possible (in that anything, to some degree is remotely possible) that the rim is so far out of spec that tire could just roll off. But for this to happen, it would have to be SO far out of spec that when you inflated it, it would be very hard to keep the tire on the rim, without a tube coming out between the rim and the tire.
I would agree with 'tunnelrat' and guess that it was a incorrectly mounted tire, and that the wheel itself, in this case, is probably not at fault.