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How long should a road tyre be able to maintain a pressure of around 100psi, and what factors are likely to reduce this time?

Background:

My tyre pressures are consistently dropping to around 60psi after about a week (three commutes, total ~50 miles), which makes the bike feel sluggish and less responsive.

I've only recently got a road bike, but I've always had mountain bikes - they've always held around 30 psi for weeks and weeks with no problems. I'm wondering if it's the higher pressure that's causing my tyres to need inflating more frequently, or something else?

This answer to another question, and some other answers I've seen suggest that you should check your tyre pressure every day, but is this to be cautious or are you likely to actually have to inflate your tyres every day?

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What size of tires are you using? –  darkcanuck Sep 23 '10 at 16:28
    
700x23 @ 100-110psi, standard (cheap) butyl tubes. –  Will Sep 23 '10 at 17:24
    
I guess it's experience, but I just give my tires a squeeze check before I head out on short rides/commuting and pump them up if they don't feel right. For long rides I pump 'em up regardless. –  user313 Oct 6 '10 at 18:56
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8 Answers

up vote 25 down vote accepted

Do yourself a huge favor, inflate them daily.

As they are high pressure and low volume they tend to lose air quicker than that of a tube that is low pressure and high volume (MTB).

With daily inflation checks you will vastly reduce the instances of pinch flats, which imo are typically the result of too low pressure. Butyl tubes, the typical tube, retain their pressure better than their Latex counterpart but still ... check regularly.

http://bicycles.stackexchange.com/questions/731/is-there-a-difference-in-having-tires-filled-with-co-vs-air
This touches on why your tyres leak down (solubility etc).

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Thanks - the high pressure/volume difference is kinda what I expected... sounds like more pumping for me! I'll monitor them a bit more closely in future. –  Will Sep 23 '10 at 14:38
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Inflating daily might be a bit more work that necessary. Inflate them before every ride. From my experience with 700x25c tires at 115 PSI, I find they lose about 5 PSI after 24 hours, just due to the natural properties of the rubber.

I ride a few times a week, and it's part of my standard pre-ride checklist to give each tire about 3-4 strokes on the floor pump, or whatever it takes to get them back up to 115.

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+1 for being specific - I'm seeing a similar rate of deflation, so it's good to know I'm not a special case. Thanks! –  Will Sep 23 '10 at 14:41
    
my 700-23c times are best at 120psi. Seems like 1-2 days later they are down to 100psi and stabilize there. Or at least the rate of deflation tapers off. –  Jay Sep 26 '10 at 4:43
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My recommendation is that road bikes get inflated before the first ride of each day. With lower pressure mountain bike tires I find that the pressure is acceptable if I've inflated them within the last 7 days.

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Another thing is that it is highly worthwhile investing in a good track pump. Here in Australia you can get a reasonable one for around 70-80 AUD. With a track pump it takes only a minute or two to top up the tyres and check their pressure.

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Yeah, definitely use a good floor pump of some sort. One with a built-in pressure gauge, and a quick-release chuck. –  Daniel R Hicks Aug 3 '11 at 15:12
    
Is a track pump the same as a floor pump? –  JFA Mar 9 at 22:26
    
Yep, a track pump is a floor pump. Definitely one of the best investments you can make for looking after your bike. –  deemar Apr 1 at 20:27
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With 700x28 tires @ 110psi, I only inflate them about once every two weeks (if I remember), or right before a major ride. I always give the tires a quick squeeze before every ride just to make sure neither has developed a slow leak.

Daily inflation, or before every ride seems like overkill to me. When you connect a pump or gauge to measure your tire pressure, you're probably losing up to 5psi just from air used to fill the pump/gauge (plus any leakage while getting them lined up right). This gets worse the smaller your tires are.

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I'm used to losing pressure when attaching a pump to a Schrader valve, but I haven't found this so far with Presta. Perhaps it's just my pump, but I actually need to exert some pressure before the valve will open and I can get a reading - at this point the connection is already airtight and I've filled the gauge/pump. Worth considering all the same - I may test this a few times tomorrow, and see what I'm losing! –  Will Sep 23 '10 at 17:31
    
I've found that road bike tires will drop about 30 psi after 24 hours. They still feel reasonably firm, but are definitely not where they should be. –  Brian Knoblauch Sep 24 '10 at 13:07
    
@Brian Knoblauch: We must be doing different things, because there's no way I'm losing 30psi over 24 hours, or even over 2 weeks. Maybe its the wider tires or thicker tubes? –  darkcanuck Sep 24 '10 at 14:35
    
I'm wondering if temperature has anything to do with it? I'd expect high temperature variation to cause the tyre to lose pressure quicker... what's the climate like where you guys live? –  Will Sep 25 '10 at 8:02
    
I question the effectiveness of a "squeeze test" at 110psi. I'm guessing they've dropped to about 80 before you notice they feel soft. –  Daniel R Hicks Aug 3 '11 at 15:15
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With 23s at 100psi you may need to inflate daily. My 35s run at 100psi and I need to inflate every 3-4 days, and relative leakage rate increases as tire width decreases.

But two things:

  • Use decent quality tubes, and beware of some brands. Some "racing" tubes are very thin and leak very rapidly. Ask the guy at your LBS which brands they get complaints about and stay away from them.
  • Don't over-tighten the valve. There is a rubber gasket in the valve that can be damaged by over-tightening. Air pressure is sufficient to hold the valve closed, and the nut is there just to secure the valve on bumps, etc.
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I use 700x23c tires with 120 psi recommended. In my experience my tires lost about 5-10 psi in a day with riding and slightly more if I don't ride for a day or two. I check the pressure and fill it to recommended before every ride.

Avoid pinch flats, and damage to wheel-set, check and fill tires to right pressure before each ride.

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the figures you'd quoted seem to be normal, i check and pump mine at least once every 3 days when i used to ride regularly. unlike car tyres the bike tubes have much lower material density but the pressure held inside is 3x higher than your typical city car tyres ... if you are really paranoid, get some commuter grade tubes which have thicker walls hopefully they hold the air longer, another possibility is that you have a crooked valve, in that case you need to replace the tube too.

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