|
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
tire width, rim width, and pressure
I've got a 32mm tire on a rim that's a bit too narrow for it, as I
found when the bead lifted off and the tube blew out, shortly after riding through a sharp curve downhill with a camping load on the bike. Funny enough, the blowoff didn't happen in the turn, but about 100 yards after. My question is, is such a blowoff more likely with higher or lower pressures? On the one hand, seems like because wide tires aren't 'hooked' in as well where the tire bead meets the rim hook at an awkward angle, a higher pressure might make it more likely to blow. On the other hand, seems like a lower pressure would allow the tire to squirm around more, esp. when side loaded, and might let the bead walk off and blow. I pumped to a somewhat lower pressure after replacing the tube, but didn't encounter any more such turns, so I wonder if that was the right move. -pm |
Ads |
#2
|
|||
|
|||
tire width, rim width, and pressure
On May 15, 9:13*pm, pm wrote:
I've got a 32mm tire on a rim that's a bit too narrow for it, as I found when the bead lifted off and the tube blew out, shortly after riding through a sharp curve downhill with a camping load on the bike. Funny enough, the blowoff didn't happen in the turn, but about 100 yards after. My question is, is such a blowoff more likely with higher or lower pressures? On the one hand, seems like because wide tires aren't 'hooked' in as well where the tire bead meets the rim hook at an awkward angle, a higher pressure might make it more likely to blow. On the other hand, seems like a lower pressure would allow the tire to squirm around more, esp. when side loaded, and might let the bead walk off and blow. I pumped to a somewhat lower pressure after replacing the tube, but didn't encounter any more such turns, so I wonder if that was the right move. -pm I'd venture that the tire simply wasn't seated. You should be able to safely run 32mm tires on virtually any rim short of wide downhill models. I mean--xcrossers run 35mm knobbies on skinny rims all the time. |
#3
|
|||
|
|||
tire width, rim width, and pressure
On Fri, 15 May 2009 18:18:22 -0700 (PDT), landotter wrote:
On May 15, 9:13*pm, pm wrote: I've got a 32mm tire on a rim that's a bit too narrow for it, as I found when the bead lifted off and the tube blew out, shortly after riding through a sharp curve downhill with a camping load on the bike. Funny enough, the blowoff didn't happen in the turn, but about 100 yards after. My question is, is such a blowoff more likely with higher or lower pressures? On the one hand, seems like because wide tires aren't 'hooked' in as well where the tire bead meets the rim hook at an awkward angle, a higher pressure might make it more likely to blow. On the other hand, seems like a lower pressure would allow the tire to squirm around more, esp. when side loaded, and might let the bead walk off and blow. I pumped to a somewhat lower pressure after replacing the tube, but didn't encounter any more such turns, so I wonder if that was the right move. -pm I'd venture that the tire simply wasn't seated. You should be able to safely run 32mm tires on virtually any rim short of wide downhill models. I mean--xcrossers run 35mm knobbies on skinny rims all the time. I'll agree, 32 isn't too wide for any of the more normal clincher rims. But then my experience is with relatively low pressure, like 50-60 pounds at most and much less for 'cross or off road. |
#4
|
|||
|
|||
tire width, rim width, and pressure
pm wrote:
I've got a 32mm tire on a rim that's a bit too narrow for it, as I found when the bead lifted off and the tube blew out, shortly after riding through a sharp curve downhill with a camping load on the bike. Funny enough, the blowoff didn't happen in the turn, but about 100 yards after. My question is, is such a blowoff more likely with higher or lower pressures? On the one hand, seems like because wide tires aren't 'hooked' in as well where the tire bead meets the rim hook at an awkward angle, a higher pressure might make it more likely to blow. On the other hand, seems like a lower pressure would allow the tire to squirm around more, esp. when side loaded, and might let the bead walk off and blow. I pumped to a somewhat lower pressure after replacing the tube, but didn't encounter any more such turns, so I wonder if that was the right move. If you habitually spin the wheel at eye level during mounting (at half pressure and again at full pressure) before installing it in your bicycle, you'll avoid the overwhelming bulk of 'mystery' blowoffs. Note each tire has a molded line just above the braking surface. That molded line must be even and visible all the way around. Where it disappears, the tire is below its proper seat and hence can, and likely will, lift over the top somewhere else. At an inconvenient time (c.f. 'Murphy') Moreover, 'mystery' tire casing tear failures are frequently attributable to brake shoe cuts just at the rim edge. These torn areas will be visible before they are fatal. Noting that damage early allows you to replace the tire and properly adjust brake pad height at your convenience, rather that just past the middle of nowhere. In the rain. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#5
|
|||
|
|||
tire width, rim width, and pressure
On May 16, 7:56*pm, AMuzi wrote:
torn areas will be visible before they are fatal. Noting that damage early allows you to replace the tire and properly adjust brake pad height at your convenience, rather that just past the middle of nowhere. In the rain. When in the phone you carry on the bike to call a taxi on days like this the battery has run out of charge. -- Andre Jute |
#6
|
|||
|
|||
tire width, rim width, and pressure
On 16 May, 05:13, wrote:
someone wrote: Funny enough, the blow-off didn't happen in the turn, but about 100 yards after. You probably had a combination heating and loading blowout, typical for descents using a lot of braking because there are many curves that do not allow higher speed that would more quickly cool the rim. Nor do they correct a flexxy wheel. Because pressure is a large part of blow-off, higher pressure is not a protection against it. Increasing a wheels rigidity reduces blow-off. Not to worry, it squirms enough either way. *I just blew a 25mm tire "Continental Gatorskin" off an MA-2 on a steep trail, causing a 10" rip in the tube. *It was loud! *I put a spare tube in and continued with more care to not overheat rims. * After all these years, you should realise that the heating is only partially the answer. The main reason your tyres blow off is because they lack sufficient rigidity for you and your riding style. Buy a pair of well built wheels whoose tyres do not blow off. someone. |
#7
|
|||
|
|||
tire width, rim width, and pressure
|
#8
|
|||
|
|||
tire width, rim width, and pressure
|
#9
|
|||
|
|||
tire width, rim width, and pressure
|
#10
|
|||
|
|||
tire width, rim width, and pressure
|
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
tyres - width/tube/pressure | Mr Clever | Techniques | 13 | August 27th 07 12:40 PM |
tyres - width/tube/pressure | Mr Clever | Australia | 5 | August 27th 07 03:19 AM |
Newbie query re rim width vs. tire width (longish) | [email protected] | Techniques | 4 | April 9th 07 01:42 PM |
MTB - Rim width vs. Tire width | Ned Mantei | Techniques | 5 | July 11th 04 12:01 AM |
Matching tire width to rim width. | mscalisi | Unicycling | 4 | April 15th 04 05:48 PM |