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Tire Pressure
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 2009-07-09 9:52 AM |
Regular  87  Beaumont |  Subject: Tire PressureWill to much tire pressure cause a flat? I generally use 120psi and had no problems earlier this year. Now that it is much hotter outside, I have had several "flats" but cant find any puncture holes in my tubes. It seems to always happen about 12-15 miles into my rides. |
| 2009-07-09 11:41 AM in reply to: #2272763 |
Extreme Veteran 1030 West Windsor, NJ | Subject: RE: Tire Pressure Absolutely. You are blowing out the tube. I would try running at 110 and see how you go. Go too low, and you risk a pinch flat. But running at 120 (cold pressure) could easily blow a tube after 12-15 miles of riding on hot pavement. |
| 2009-07-09 11:49 AM in reply to: #2272763 |
Veteran 263 | Subject: RE: Tire Pressure I can't imagine too much pressure alone would cause a flat. Have you put the tubes in water to test for a tiny hole? There must be a hole somewhere if the air is escaping. Regarding air pressure in general, however, the pressure will increase significantly in hot weather. If you are inflating your tires in a climate that is a lot cooler than what you will be riding in (eg in an air conditioned house), you should not inflate them as fully as you normally would, as they will expand when you go out in the hot air. |
| 2009-07-09 11:59 AM in reply to: #2272763 |
Not a Coach 11473 Media, PA | Subject: RE: Tire Pressure Higher pressure increases risk of flats. Won't necessarily "cause" it, but might contribute. In training I run ~100-110 and go up to ~115 when racing. |
| 2009-07-09 12:01 PM in reply to: #2272763 |
Master 1359 South of SLC | Subject: RE: Tire Pressure Just follow the manufacturer's guidelines and avoid potholes and slow down at railroad tracks. Check the inside of your tire to make sure you don't have a burr or glass left in. A couple of years ago I flatted three times on the same ride and it was because I had a thorn stuck in my tire. I always check tires when I have a flat now! Mike |
| 2009-07-09 3:33 PM in reply to: #2272763 |
Extreme Veteran 657 | Subject: RE: Tire Pressure I weigh about 195. If I don't fill my tires up to 120 I'll flat out on these little white rocks that TxDot seems to scatter along the shoulders of most roads around where I ride. I had a tire suddenly lose about 60lbs of pressure while riding. It didn't have an obvious leak, but when I inflated it and put the tube under water there was a leak where the stem attaches to the tube. I'm wondering if when I pumped it up I didn't wiggle the stem too much. |
| 2009-07-09 3:45 PM in reply to: #2272763 |
Champion 9407 Montague Gold Mines, Nova Scotia | Subject: RE: Tire Pressure It is likely that you have a small object embedded in your tire or you have bad rim tape. If your are flatting then there is definitely a hold in your tube so the next time (or if you still have one of your flats) inflate it until you find the leak. If it is a slow leak, some soapy water can be your best friend in finding the leak. As for the pressure, even if we take an extreme example, according to the ideal gas law (PV=nRT) where T is measure in Kelvin, a change of 50K (90F) is about 7.25psi difference so unless you are blowing the bead off the rim (unlikely unless you are running above the max recommended psi) then it is not likely the pressure that is causing your flats. Shane |
| 2009-07-10 12:43 AM in reply to: #2274225 |
| 154 | Subject: RE: Tire Pressure gsmacleod - 2009-07-09 3:45 PM hahaha I love it...chemistry in action right here folks.It is likely that you have a small object embedded in your tire or you have bad rim tape. If your are flatting then there is definitely a hold in your tube so the next time (or if you still have one of your flats) inflate it until you find the leak. If it is a slow leak, some soapy water can be your best friend in finding the leak. As for the pressure, even if we take an extreme example, according to the ideal gas law (PV=nRT) where T is measure in Kelvin, a change of 50K (90F) is about 7.25psi difference so unless you are blowing the bead off the rim (unlikely unless you are running above the max recommended psi) then it is not likely the pressure that is causing your flats. Shane |
| 2009-07-10 9:41 AM in reply to: #2273273 |
Expert 1296 | Subject: RE: Tire Pressure JohnnyKay - 2009-07-09 12:59 PM Higher pressure increases risk of flats. Won't necessarily "cause" it, but might contribute. In training I run ~100-110 and go up to ~115 when racing. Woooow really? That's very interesting. I usually always go to 120 psi on my training wheels no matter what it is. I think some common sence applies to the OP question. I ususally pump up before every ride that I do. I also spin the wheels to see what they look like, review tread wear, any puncture marks, make sure they look good. I guess if you live in a very hot climate it might be a huge issue. But I've always gone right to or slightly above 120 and have flatted maybe 2 time in 4 years. Race wheels go right up to the max the tire can handle. I usually bring them up to 140-150..... Edited by gadzinm 2009-07-10 9:43 AM |
| 2009-07-10 9:44 AM in reply to: #2272763 |
Expert 1296 | Subject: RE: Tire Pressure Oh any by the way now that I opened my big mouth about only flatting 2 times in 4 years you can bet any amount of $$$$ that I am due in the next few rides!!! LOL |
| 2009-07-10 9:47 AM in reply to: #2275928 |
Resident Curmudgeon 25290 The Road Back Gold member | Subject: RE: Tire Pressure gadzinm - 2009-07-10 9:41 AM JohnnyKay - 2009-07-09 12:59 PM Higher pressure increases risk of flats. Won't necessarily "cause" it, but might contribute. In training I run ~100-110 and go up to ~115 when racing. Race wheels go right up to the max the tire can handle. I usually bring them up to 140-150..... There's some research out there that shows you actually lose some efficiency at those higher pressures, due to loss of contact with the road, IIRC. Not to mention the harsher ride. |
| 2009-07-10 9:54 AM in reply to: #2275950 |
Expert 1296 | Subject: RE: Tire Pressure the bear - 2009-07-10 10:47 AM gadzinm - 2009-07-10 9:41 AM JohnnyKay - 2009-07-09 12:59 PM Higher pressure increases risk of flats. Won't necessarily "cause" it, but might contribute. In training I run ~100-110 and go up to ~115 when racing. Race wheels go right up to the max the tire can handle. I usually bring them up to 140-150..... There's some research out there that shows you actually lose some efficiency at those higher pressures, due to loss of contact with the road, IIRC. Not to mention the harsher ride. Thanks. Yeah I have read some of it but it must be the fact that I am Polish or something. I still love to fire them up to 130-150 pending the course and temps on race day. I played around with it a few times a few years ago in training and the Vredestein Fortezza TriComp's that I have just seem to perform the best at that range with my H3's. Who knows though. |
| 2009-07-10 9:55 AM in reply to: #2275928 |
Not a Coach 11473 Media, PA | Subject: RE: Tire Pressure gadzinm - 2009-07-10 10:41 AM JohnnyKay - 2009-07-09 12:59 PM Higher pressure increases risk of flats. Won't necessarily "cause" it, but might contribute. In training I run ~100-110 and go up to ~115 when racing. Woooow really? That's very interesting. I usually always go to 120 psi on my training wheels no matter what it is. I think some common sence applies to the OP question. I ususally pump up before every ride that I do. I also spin the wheels to see what they look like, review tread wear, any puncture marks, make sure the look good. I guess if you live in a very hot climate it might be a huge issue. But I've always gone right to or slightly above 120 and have flatted maybe 2 time in 4 years. Race wheels go right up to the max the tire can handle. I usually bring them up to 140-150..... I do have a hard time believing 120 is causing the OP a big problem, but higher pressures do increase flat risk (just as lower pressures do with regard to pinch flats). And it is possible for the pressure to rise further due to ambient/road heat and/or braking. On most road surfaces (i.e., those that aren't track-like smooth), you will be better off with your training pressure than your race pressure (depends somewhat on the tire and, of course, rider weight but somewhere in the 100-130 range is probably best for most). The 140-150 will reduce the tires' rolling resistance, but you will likely lose out due to "bouncing" along the imperfections in the road instead of having the tire deflect and roll smoothly. |
| 2009-07-10 10:08 AM in reply to: #2275982 |
Expert 1296 | Subject: RE: Tire Pressure JohnnyKay - 2009-07-10 10:55 AM gadzinm - 2009-07-10 10:41 AM JohnnyKay - 2009-07-09 12:59 PM Higher pressure increases risk of flats. Won't necessarily "cause" it, but might contribute. In training I run ~100-110 and go up to ~115 when racing. Woooow really? That's very interesting. I usually always go to 120 psi on my training wheels no matter what it is. I think some common sence applies to the OP question. I ususally pump up before every ride that I do. I also spin the wheels to see what they look like, review tread wear, any puncture marks, make sure the look good. I guess if you live in a very hot climate it might be a huge issue. But I've always gone right to or slightly above 120 and have flatted maybe 2 time in 4 years. Race wheels go right up to the max the tire can handle. I usually bring them up to 140-150..... I do have a hard time believing 120 is causing the OP a big problem, but higher pressures do increase flat risk (just as lower pressures do with regard to pinch flats). And it is possible for the pressure to rise further due to ambient/road heat and/or braking. On most road surfaces (i.e., those that aren't track-like smooth), you will be better off with your training pressure than your race pressure (depends somewhat on the tire and, of course, rider weight but somewhere in the 100-130 range is probably best for most). The 140-150 will reduce the tires' rolling resistance, but you will likely lose out due to "bouncing" along the imperfections in the road instead of having the tire deflect and roll smoothly. I agree with what you are saying I was not disagreeing I was just a little surprised to see that you ride a lower tire pressure. I'll give 130 a shot and see how that works out. I do know that the last time I had a flat I was riding at 120 when I flatted. (Ran over a staple in the middle of farm roads, WTF) Once I got the tire changed and filled with the compressed air it only went to 100 psi. My average speed for the rest of the ride was almost 2 MPH less than when I was at 120. Now, I have no way to "scientifically" prove this but I clearly was struggling with the lower tire pressure. Who knows? |
| 2009-07-10 10:17 AM in reply to: #2276025 |
Not a Coach 11473 Media, PA | Subject: RE: Tire Pressure gadzinm - 2009-07-10 11:08 AM I agree with what you are saying I was not disagreeing I was just a little surprised to see that you ride a lower tire pressure. I'll give 130 a shot and see how that works out. I do know that the last time I had a flat I was riding at 120 when I flatted. (Ran over a staple in the middle of farm roads, WTF) Once I got the tire changed and filled with the compressed air it only went to 100 psi. My average speed for the rest of the ride was almost 2 MPH less than when I was at 120. Now, I have no way to "scientifically" prove this but I clearly was struggling with the lower tire pressure. Who knows? I don't think the differences we are talking about yield 2mph in any event.  FWIW, I ride Michelin's that have max pressure of 116. So I'm riding them right up near the limit given I'm not a lightweight. But even if I were riding yours, I probably wouldn't go much higher than 120. |
| 2009-07-10 10:20 AM in reply to: #2276054 |
Expert 1296 | Subject: RE: Tire Pressure JohnnyKay - 2009-07-10 11:17 AM gadzinm - 2009-07-10 11:08 AM I agree with what you are saying I was not disagreeing I was just a little surprised to see that you ride a lower tire pressure. I'll give 130 a shot and see how that works out. I do know that the last time I had a flat I was riding at 120 when I flatted. (Ran over a staple in the middle of farm roads, WTF) Once I got the tire changed and filled with the compressed air it only went to 100 psi. My average speed for the rest of the ride was almost 2 MPH less than when I was at 120. Now, I have no way to "scientifically" prove this but I clearly was struggling with the lower tire pressure. Who knows? I don't think the differences we are talking about yield 2mph in any event. FWIW, I ride Michelin's that have max pressure of 116. So I'm riding them right up near the limit given I'm not a lightweight. But even if I were riding yours, I probably wouldn't go much higher than 120. Must have been my lack of motivation after I flatted.... My training wheels max out at 120 and I never take them higher than that. The Verdestien's hower do say 150 but like I said over the last couple of years I have been dropping the pressure down closer to 130. When I first started out I was at 150 and the pump was about to shatter. In fact I would pull the crack pipe off the wheels and it would knock me on my .... |
| 2009-07-10 5:35 PM in reply to: #2272763 |
Expert 1040 SF Bay Area | Subject: RE: Tire Pressure Another vote for checking your rim tape. I replaced mine and now no more flats. The old tape had busted through over one of the spoke holes near the valve and that's where it was slicing the tube. Luckily, no more problems. I weigh about 225 and I usually put in 110 lbs. |
| 2009-07-10 5:58 PM in reply to: #2272763 |
| 154 | Subject: RE: Tire Pressure wait...so my tire says to inflate to 90 -100 psi and im about 205 lbs...are you guys telling me i should up that to 110-120? |
| 2009-07-10 6:13 PM in reply to: #2272763 |
Expert 1040 SF Bay Area | Subject: RE: Tire Pressure No, go by what's on the sidewall as the max. Mine says max 120, so I inflate to 110. |
| 2009-07-10 6:20 PM in reply to: #2272763 |
Pro 3932 Irvine, California | Subject: RE: Tire Pressure How does a rider's weight affect the equation? If you weigh more, should you pump the tires up a bit more (more pressure), or not go as high (less pressure) relative to someone who weighs less? |
| 2009-07-10 6:25 PM in reply to: #2277245 |
Not a Coach 11473 Media, PA | Subject: RE: Tire Pressure Tripolar - 2009-07-10 7:20 PM How does a rider's weight affect the equation? If you weigh more, should you pump the tires up a bit more (more pressure), or not go as high (less pressure) relative to someone who weighs less? More. Here's an example of guidelines from Michelin: http://www.michelinbicycletire.com/michelinbicycle/index.cfm?event=... |
| 2009-07-10 6:26 PM in reply to: #2272763 |
Master 3127 Sunny Southern Cal | Subject: RE: Tire Pressure I used to get more flats running at less than the max pressure (100 psi or so). Now I put close to max pressure and I have fewer flats. That's either 110 psi on a tire rated for 110, or 120 on a tire rated for 125. But I do some riding on gravel, and there are seasonally some nasty thorns that I have to contend with. For whatever reason, high pressure means fewer thorn punctures. So far I haven't adjusted pressures down for summer temps, but I mostly ride in the morning when it's still not too hot. |
| 2009-07-10 6:32 PM in reply to: #2277253 |
Pro 3932 Irvine, California | Subject: RE: Tire Pressure JohnnyKay - 2009-07-10 4:25 PM Tripolar - 2009-07-10 7:20 PM How does a rider's weight affect the equation? If you weigh more, should you pump the tires up a bit more (more pressure), or not go as high (less pressure) relative to someone who weighs less? More. Here's an example of guidelines from Michelin: http://www.michelinbicycletire.com/michelinbicycle/index.cfm?event=... /> Awesome, thanks for that link! I've been inflating my Michelin Pro Race 2's to around 120, so looks like I'm about right -- I weigh just over 200. |
| 2009-07-10 8:07 PM in reply to: #2272763 |
| 6 | Subject: RE: Tire Pressure going to jack this thread for another question about tire pressure: I use a floor pump, i believe it's made by specialized. When I go to pump my tubes up very frequently the PSI spikes as i add more air and then the needle drops back to 0 where it stays until i pump more air, then it spikes etc. Keep in mind, the tubes inflate as i do this, but i do not know how inflated they are; typically i just pump them up until they feel pretty hard and then go for a ride but it's frustrating not knowing. anyone encounter this / have an easy fix? |
| 2009-07-10 10:40 PM in reply to: #2272763 |
Veteran 298 Rockwall, Texas | Subject: RE: Tire Pressure Duck: i had this problem for a while. unscrew the top part of the presta valve and make sure the hose valve is seated well on the tube's valve stem. what's happening is that the pump valve isnt seated correctly or the presta valve isnt unscrewed all the way and the spike in pressure is inside of the pump tube, and that air just barely leaks into your tire. make sure the valve stem is unscrewed and your pump valve us seated well. it should give you a reading then for the tire pressure.  Edited by generalee2010 2009-07-10 10:42 PM |
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