Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Do you deflate your tires when your bike is in the sun?

Notices
Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Do you deflate your tires when your bike is in the sun?

Old 09-09-03, 08:11 AM
  #1  
trmcgeehan
Senior Member
Thread Starter
 
trmcgeehan's Avatar
 
Join Date: Oct 2002
Location: Somerset, KY -- near Lake Cumberland
Posts: 757

Bikes: 1980 Univega; 1985 Ross; 1994 Trek 1400 -- all road bikes

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Do you deflate your tires when your bike is in the sun?

I recently took a 750 mile trip from Kentucky to the Outer Banks of North Carolina. My bike was on a rack in the back. I read somewhere that you should not park your bike in the sun over long periods of time because the heat expansion will blow the tires. So half way through the trip, I deflated both tires, only to find that letting a little air out takes the tire from 110 pounds down to 70 or 80. I stopped at a LBS, and the wrench there said I needn't worry. He said most bike tires are designed to take DOUBLE the recommended maximum inflation pressure. If he's right, my Michelin Axial Carbons could have inflated to 220 pounds from the sun heat, and not been harmed. Is this true? Also, what effect does the air rushing over the bike tire when the car is moving have on pressure expansion? Does this negate the heat from the sun (the temp during my trip was in the low 90's).Thanks for your input.
__________________
"I am a true laborer. I earn that I eat, get that I wear, owe no man hate, envy no man's happiness, glad of other men's good, content with my harm." As You Like It, Act 3, Scene 2. Shakespeare.
"Deep down, I'm pretty superficial." Ava Gardner.
trmcgeehan is offline  
Old 09-09-03, 08:58 AM
  #2  
OregonBound
Guest
 
Posts: n/a
Mentioned: Post(s)
Tagged: Thread(s)
Quoted: Post(s)
I've biked with high pressure road tires in areas with temps in the 100+ F. range for 8 hours at a go with no problem. Have also left bikes parked in blazing sun all day with no damage to the tires/tubes. Can't say for certain, but I've never felt a need to let air out due to temp or sun.

Paul
 
Old 09-09-03, 10:03 AM
  #3  
deliriou5
It tastes like burning!
 
deliriou5's Avatar
 
Join Date: May 2002
Location: SOUTH Jersey
Posts: 1,014
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
uh, there's no way the heat expansion could blow your tires...

anyone remember charles' law? says that pressure is directly proportional to absolute temperature. heating from 0 C to 35 C will only raise your tire pressure by 13%.

so in a nutshell, no your tires will not blow off their rims
deliriou5 is offline  
Old 09-09-03, 10:16 AM
  #4  
Paul L.
Senior Member
 
Paul L.'s Avatar
 
Join Date: Jul 2002
Location: Arizona, USA
Posts: 2,601

Bikes: Mercier Corvus (commuter), Fila Taos (MTB), Trek 660(Got frame for free and put my LeMans Centurian components on it)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I park my bike in sunlight all summer during the day. It has seen 115 degrees this summer pumped up to 118 and no problems.
__________________
Sunrise saturday,
I was biking the backroads,
lost in the moment.
Paul L. is offline  
Old 09-09-03, 03:12 PM
  #5  
Cyclepath
Senior Member
 
Join Date: Sep 2003
Location: Willimantic, Connecticut
Posts: 499

Bikes: '70s Puch sport tourer, '90 Peugeot Success.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
The only danger to your bike from solar radiation is that it will cause your tires & brakepads to deteriorate somewhat faster, & also may fade your paint. I park my bike out of the sun whenever possible.
Cyclepath is offline  
Old 09-09-03, 03:36 PM
  #6  
Dave Stohler
60mph in the 42 ring!
 
Dave Stohler's Avatar
 
Join Date: Jul 2003
Location: Niagara Frontier, NY
Posts: 546
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time in 1 Post
This post is a joke, isn't it?
Dave Stohler is offline  
Old 09-09-03, 05:18 PM
  #7  
miamijim
Senior Member
 
miamijim's Avatar
 
Join Date: Aug 2003
Location: Tampa, Florida
Posts: 14,002
Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 371 Post(s)
Likes: 0
Liked 26 Times in 22 Posts
Dave, I wouldnt call this a joke. When I worked in the buisness custumoers asked us this all the time. More specifically if they should let air out when the bike was in the back of the car. deleriou5 got it right with charles' law. Consider it an informative post. Heck, my car tires only go from 30 to 33.
miamijim is offline  
Old 09-09-03, 07:05 PM
  #8  
MI_rider
Go Yankees
 
MI_rider's Avatar
 
Join Date: Apr 2003
Location: Clarkston, Michigan
Posts: 153

Bikes: Bianchi Volpe, Trek 2300

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
The question probably gets asked here frequently in different forms. I remember a few months back someone posted and was worried their tires would blow at the top of a mountain if they started at the bottom of the mountain with them at full pressure.
MI_rider is offline  
Old 09-09-03, 08:13 PM
  #9  
dexmax
road siklista
 
dexmax's Avatar
 
Join Date: Apr 2003
Location: Perlas ng Silanganan
Posts: 1,469

Bikes: Custom Knolly Chilcotin Limited Edition Orange, Dartmoor Wish, KHS 7500, Custom built Specialized Camber, S-Works Road, Cannondale Trail mtb, Polini MTB

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
pressure vessels including tires have a 2-3.5 factor of safety depnding on the design pressure and volume..

That's about 100psi more.
dexmax is offline  
Old 09-09-03, 08:41 PM
  #10  
mike
Senior Member
 
mike's Avatar
 
Join Date: Jul 2000
Location: Snowy midwest
Posts: 5,392
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally posted by deliriou5
uh, there's no way the heat expansion could blow your tires...

so in a nutshell, no your tires will not blow off their rims
Deliriou5, I always like your posts, but I have to advise you and others that the sun/heat CAN blow the tires of your rims. It happened to my friend. We were on a tour and had ridden about four hours. I had inflated our tires in the cool morning. The day grew hotter.

We took a break at noon and leaned our bikes outside against a big window at a resturaunt. The bikes were in the sun and we sat next to the window so we could watch our bikes.

All of a sudden KAWHAMEE!! there was like an explosion against the window. Everybody inside the resturaunt jumped (most of all my friend and me!).

Somebody thought that a pelican must have flown into the window. Further inspection revealed that the rear tire on my friend's bike had exploded. The tire was blown off the rim and the tube was shredded.

Thanks to some kind help from a locals, we bought a replacement at the only hardware store in town (no bike shops in that town AND the hardware store had a couple of tires).

Here are some factors:

1) The tires were 27" with a max inflation of 90 lbs.
2) I filled the tires to 90 lbs - maybe just a pound over
3) The failed tire was not new (don't know how old).
mike is offline  
Old 09-09-03, 08:43 PM
  #11  
miamijim
Senior Member
 
miamijim's Avatar
 
Join Date: Aug 2003
Location: Tampa, Florida
Posts: 14,002
Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 371 Post(s)
Likes: 0
Liked 26 Times in 22 Posts
Mike...repeat, repeat, repeat.....that tire did not blow because of a pressure inrease due to heat!!!!!
miamijim is offline  
Old 09-09-03, 08:47 PM
  #12  
mike
Senior Member
 
mike's Avatar
 
Join Date: Jul 2000
Location: Snowy midwest
Posts: 5,392
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally posted by miamijim
Mike...repeat, repeat, repeat.....that tire did not blow because of a pressure inrease due to heat!!!!!
So... are you saying a pelican did it?
mike is offline  
Old 09-09-03, 08:55 PM
  #13  
miamijim
Senior Member
 
miamijim's Avatar
 
Join Date: Aug 2003
Location: Tampa, Florida
Posts: 14,002
Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 371 Post(s)
Likes: 0
Liked 26 Times in 22 Posts
I'm saying something other than the heat did it.......actually the only way heat could have done it, and its very un-likely it happened is if the gumwall sidewalls melted. That may have contributed to the failure but it DID NOT happen due to an increase in pressure.

Something to keep in mind is that pressure increase due to heat is even regardless of the temperature. In other words if the temp goes from 0 to 100 thats the same as it going from 100 to 200. My car tires are 30 degrees when the temp is 85. After they heat uo to what, 150 degrees? They only go up to 33 degrees. 35C degree change 13% pressure change......see above..
miamijim is offline  
Old 09-09-03, 11:00 PM
  #14  
Cyclepath
Senior Member
 
Join Date: Sep 2003
Location: Willimantic, Connecticut
Posts: 499

Bikes: '70s Puch sport tourer, '90 Peugeot Success.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
The blowout could also have resulted from a defective/old tube, combined with heating.

I've read that rated bike tire pressures are determined by inflating the tire until it blows off the rim. The rating is then marked at half of that pressure.
Cyclepath is offline  
Old 09-10-03, 07:49 AM
  #15  
lotek 
Senior Member
 
lotek's Avatar
 
Join Date: Dec 2001
Location: n.w. superdrome
Posts: 17,688

Bikes: 1 trek, serotta, rih, de Reus, Pogliaghi and finally a Zieleman! and got a DeRosa

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
I seem to recall that there was some discussion of
tire pressure and heat around Hotter Than Hell. I've been
looking for the reference but can't find it.
The premise was that due to high heat on the road (up to
140 degrees at surface) there are more blow outs due to
the changes in pressure. The writer mentioned dropping
tire pressure by about 5 - 10 psi for the ride.
All I know is I saw more blow outs
on HHH (both last year and this year) than one would expect
to see for a ride of that size.
Interesting topic tho, and no I don't think this question is
a troll.
I'll continue to search for the article and if I find it I'll post it
(if soft copy).

Marty
__________________
Sono pił lento di quel che sembra.
Odio la gente, tutti.


Want to upgrade your membership? Click Here.
lotek is offline  
Old 09-10-03, 10:35 AM
  #16  
roadbuzz
Just ride.
 
roadbuzz's Avatar
 
Join Date: Oct 2000
Location: C-ville, Va
Posts: 3,258
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked 0 Times in 0 Posts
Well, I don't know about the physics or what, but I *have* had bike tires blow, twice, when the bike was stored in the back of a station wagon, windows mostly closed, parked in the sun, during a Virginia summer. Say what you will, it wasn't pelicans! I didn't believe it would be possible either, but was told by a local shop monkey that it happens all the time.
roadbuzz is offline  
Old 09-10-03, 11:33 AM
  #17  
Cyclepath
Senior Member
 
Join Date: Sep 2003
Location: Willimantic, Connecticut
Posts: 499

Bikes: '70s Puch sport tourer, '90 Peugeot Success.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Due to the greenhouse effect, the inside of a vehicle can get much hotter than the
ambient air outside. Failure might be due more to weakening of the rubber than to pressure increase.
Cyclepath is offline  
Old 09-10-03, 07:25 PM
  #18  
roadbuzz
Just ride.
 
roadbuzz's Avatar
 
Join Date: Oct 2000
Location: C-ville, Va
Posts: 3,258
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked 0 Times in 0 Posts
Granted. I think the heat inside the closed vehicle was the kicker in my case.
roadbuzz is offline  
Old 09-10-03, 07:42 PM
  #19  
allgoo19
Deported by koffee
 
allgoo19's Avatar
 
Join Date: Aug 2003
Location: So. Cal
Posts: 1,187
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
It's not the rubber that is holding the tire in one piece under high pressure but the thread.

I had seen my tire blew up right in front of my eyes while I was at roadside watching a parade. I knew my tire had a cut on the side wall but I had it for long time, I didn't think it was going blow up. I could see the tube came out like a balloon slowly then finally blew up. I was so embarrassed to see people looking at my way as if I shot a gun in the public. I just told everybody around me that my tire blew up.

Someone here said the normal tires hold twice the maximum pressure it states and I believe that. Once you get flat tire, it's not only the tube that got damaged but also the tire covers over it. Once it gets damaged that spot will be the weakest part. It'll take a great effort to tear a piece of cloth by hands but once you cut the edge by scissors, you can tear it all the way across effortlessly. The same thing applies to tires. Once foreign object pierce through the tire and break a thread or two, the neighboring thread will get greater stress than the rest, then eventually breaks thread by thread. You can patch a tire from inside but it's not nearly strong as a threaded tire wall.

So, my answer to the original question is to keep a spare tire if you use a tire that already had a flat, or if you can afford it, replace it once you get a flat, instead of keep repeating inflate then de-flate the tire.
__________________
Originally Posted by allgoo19
Originally Posted by sydney
Sydney gots ramped rings with no 'cutouts'.What's up with that?
It's "sydney". You must be new. ;)
Good ol' days...

Last edited by allgoo19; 09-10-03 at 07:59 PM.
allgoo19 is offline  
Old 09-10-03, 08:58 PM
  #20  
sch
Senior Member
 
Join Date: May 2003
Location: Mountain Brook. AL
Posts: 3,826
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 253 Post(s)
Likes: 0
Liked 70 Times in 54 Posts
Miamijim: The reference by Mike to 27" tires makes me wonder if they were
older, non hook bead tire/rims. These were more sensitive to pressure than the hook beads we all use now.

On another thought: after watching the horror show of Beloki's crash and the suggestion that heat rolled his tire. So I felt my rims after braking from 25mph to 5mph on a downhill over ~200yds. The rims felt like 120F, you could touch and grip them but after 5-10sec it was too hot for comfort. Makes me wonder what the rims would do on a long curvy hilly descent (ala TDF). The upside risk is certainly more than a hot car in July. I have read threads about hydraulic brakes on tandems locking up on hilly descents from heat induced expansion of the fluid. Steve
sch is offline  
Old 09-11-03, 06:00 PM
  #21  
mike
Senior Member
 
mike's Avatar
 
Join Date: Jul 2000
Location: Snowy midwest
Posts: 5,392
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally posted by sch
Miamijim: The reference by Mike to 27" tires makes me wonder if they were
older, non hook bead tire/rims. These were more sensitive to pressure than the hook beads we all use now. Steve
Yes, in my case, the tire was old. I don't know how old, but let's say that a woman born the same year as the tires could probably bear children today.

For the record, the tire was a hook/bead tire, but 'ya', I know what Steve means about the really old rims that were not hook/bead. Those blew tires especially easily.
mike is offline  
Old 09-11-03, 06:42 PM
  #22  
Dave Stohler
60mph in the 42 ring!
 
Dave Stohler's Avatar
 
Join Date: Jul 2003
Location: Niagara Frontier, NY
Posts: 546
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Ok, since (P1*T2)/T1= P2, and these #'s are in absolute (rankine or absolute temperatures, not common farenheit or celsius), lets see what the difference of a hot day over, say, a cold basement would be, shall we?

Temp basement: 50 degrees F, or 510 degrees R

Temp in hot, hot sun: 120 F, or 580 R

P2 = P1*(580/510) = 1.13P1, or 13% rise in pressure. So, 100 psig cold = 113 psig hot. Big deal.
Dave Stohler is offline  
Old 09-11-03, 07:37 PM
  #23  
miamijim
Senior Member
 
miamijim's Avatar
 
Join Date: Aug 2003
Location: Tampa, Florida
Posts: 14,002
Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 371 Post(s)
Likes: 0
Liked 26 Times in 22 Posts
More than likely this was an isolated blow-out that would have happened regardless of where the bike was.

sch, good thought on the non-hook bead rims. If they were, a 20 p.s.i. change could have been the culprit.
miamijim is offline  
Old 01-01-06, 10:19 AM
  #24  
apollo7
Newbie
 
Join Date: Jan 2006
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Twice I have seen tires(actually heard them) blow because they were in the sun. Both times they were tubular type tires. Once was in Atlanta, middle of summer at the Mayors Cup race. A few riders had their bikes leaning against a building in the sun. We all heard them blow. Sounded like a gun.

The other time was after descending Brasstown Bald. We stopped at the bottom waiting on the uphill time trial. I think it was the heat from all the braking going down hill and then letting them sit in the sun.

Apollo
apollo7 is offline  
Old 01-01-06, 10:31 AM
  #25  
urban_assault
53 miles per burrito
 
urban_assault's Avatar
 
Join Date: Sep 2001
Location: Ft Worth, TX
Posts: 1,488

Bikes: Land Shark, Trek 1000, Iron Horse Rogue, Novara Randonee

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by apollo7
Twice I have seen tires(actually heard them) blow because they were in the sun. Both times they were tubular type tires. Once was in Atlanta, middle of summer at the Mayors Cup race. A few riders had their bikes leaning against a building in the sun. We all heard them blow. Sounded like a gun.

The other time was after descending Brasstown Bald. We stopped at the bottom waiting on the uphill time trial. I think it was the heat from all the braking going down hill and then letting them sit in the sun.

Apollo
Welcome to the forums Apollo. Let's not make a habit of digging up 3 year old threads.
urban_assault is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.