Tyre Pressures

[buckwhelk]

I'm looking for advice regarding tire pressures. I have Bontrager AW1 Hard Case Lite 700x32 tires on my bike. On the tire it says inflate to 55-100 psi. For "normal" road riding, what pressure should I inflate the tires to? When would I need to inflate to 100 psi? All advice greatly appreciated.

[moonoi]

It's dependent on a couple of factors, the main one being your weight.


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[StreetCowboy]

I'd recommend Run them hard, if you can.

I reckon you'll get less punctures.

 

I keep mine up at the top end of their rating, 

But then, I'm lucky I've got plenty of padding on my backside...

 

32mm tyres are probably meant for tarmac or dirt roads; on dirt you'd want a lower pressure to reduce risk of skidding on corners, I think

 

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[el jefe]

1 hour ago, moonoi said:

It's dependent on a couple of factors, the main one being your weight.


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The secondary factor is the type of road surface.

The heavier you are the closer you want to be to the top end of the pressure range.

The rougher the surface of the roads, the lower the pressure; though if you'll be bouncing thru potholes you would want higher pressure to prevent pinch flats.

And generally, you would want slightly higher pressure in the rear tire than the front.

[moonoi]

To give an example, I'm around 100-105Kg, on my race bike in the dry I run 115psi rear and 105psi front.

If it's wet/raining I'll drop that to 105 rear and 95 front.

Any less than that and as el jefe says I get pinch flats on rough surfaces.

Basically though you have to experiment a bit to see what works for you.


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[StreetCowboy]

5 hours ago, moonoi said:

To give an example, I'm around 100-105Kg, on my race bike in the dry I run 115psi rear and 105psi front.

If it's wet/raining I'll drop that to 105 rear and 95 front.

Any less than that and as el jefe says I get pinch flats on rough surfaces.

Basically though you have to experiment a bit to see what works for you.


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I'm around 100 kg and I run 32 mm tyres with 85 psi at the back and 80 psi at the front; at the top end of what is marked on the tyres - though I haven't checked my new tyre to see what is marked on it.

 

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[moonoi]

I'm running 24mm tyres, so at 32mm that would be around what I would use too, although I'd go lower at the front 70 or 75


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[StreetCowboy]

Since the front seems to carry so much less weight, I might do as you suggest, and drop the pressure a little to improve adhesion, especially on bad surfaces.

 

My last puncture was because the rear tyre was knackered, and I was running over some very rough spilled concrete.  Yesterday we were out on some equally rough broken stone roads and I was very nervous the pointy rocks would burst a tyre but we both survived - myself on the 32 mm 85 psi, and my mate on 25 mm 110 psi tyres.

Both new back tyres, though, less than 200 km old.

 

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[buckwhelk]

OK Thanks very much for all of you who replied. My body weight is pretty steady around 80Kg. I mainly ride on tarmac roads (+potholes) & concrete.

[Deserted]

You also want to take into consideration that the inner tubes on sale here on pretty damn cheap and thus more susceptible to bursting if you over-inflate them. 

[StreetCowboy]

2 hours ago, Deserted said:

You also want to take into consideration that the inner tubes on sale here on pretty damn cheap and thus more susceptible to bursting if you over-inflate them. 

Is that true?  My understanding is that generally, the tubes have plenty of girth in them, and it's the tyre that resists the pressure, and keeps them the right size.

 

I've never noticed a pressure marking on an inner tube.

 

To "over-inflate" the pressure tube, you'd need to pump it up when it was not in the tyre, and in that case a very modest pressure would 'over-inflate' it.  I normally only put a very low pressure into the tube when I'm looking for holes, and it still inflates to bigger than tyre size

 

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Edit: I was browsing in the bike shop near Rama IV between Suk. 24 - 26 (near A-Park?) and they had Kenda tubes, which is the same brand I get in Malaysia.  Chinese manufacture, and seem OK, although for some reason I have more faith in the Bontrager tubes that the Trek shop sells, but they are 50% more expensive

[Deserted]

I've had 4-5 burst here because I went over 110 psi, same brand. Changed to a more expensive one, hasn't happened yet. Maybe I just got unlucky...

[moonoi]

I use specialized, maxxis, continental and schwalbe tubes here, not had any issue as mentioned and cost from 110-180thb each


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[el jefe]

The only way a tube can burst when properly seated in a tire is if there is a small cut in the tire and the pressure forces the tube thru that tiny hole. If your tire is in good shape, then the physics of the tire holding the tube in place will prevent it from bursting even with extremely high pressure. Or, if the tire is not seated properly on the rim, a fully inflated tube will blow if off the rim, bursting the tire. back in the day, we used to run up to 160 psi on track tires and for a while when higher pressure was considered better, I used to ride road tires rated to 150 psi max. Even then, I've never had a tube burst.

[StreetCowboy]

1 minute ago, el jefe said:

The only way a tube can burst when properly seated in a tire is if there is a small cut in the tire and the pressure forces the tube thru that tiny hole. If your tire is in good shape, then the physics of the tire holding the tube in place will prevent it from bursting even with extremely high pressure. Or, if the tire is not seated properly on the rim, a fully inflated tube will blow if off the rim, bursting the tire. back in the day, we used to run up to 160 psi on track tires and for a while when higher pressure was considered better, I used to ride road tires rated to 150 psi max. Even then, I've never had a tube burst.

ON my mountain bike (which I only ever rode on the road) my frequency of punctures dropped dramatically when I bought a floor pump and went from about 40 psi or less to 80 psi.

[Nowisee]

IMO...

Over pressured tires puncture more easily (think of a tighten rope cutting easier).  They can also be skittish on bumpy corners as the tend to leave the ground.  No contact patch.
Under inflated can pinch flat if the inside rim width is significantly narrower than the tire size.  The tire sidewall bulges out and rolls too much.  

Try and ride a tire size appropriate for your weight and accompanied by a reasonable rim width.  It allows you to run lower pressures without pinch flats.  Then put in the right sized tube.  Too small of tube width creates easy punctures as the tube is maxed out.   
The best combo I had on my road bike was a rim with 19mm inside width running a 28 tire.  I could ride lower pressures and the ride was so much nicer, the bike cornered wonderfully.  
Then I went to the  ultimate in both my mtb and road bikes... tubeless...lower pressure, wider tires, no worries.  
 

 

[pagallim]

Agree with Nowisee re tubeless.   I have Schwalbe Pro One tubeless on both of my road bikes now and they are excellent.   Got them on special offer from Chain Reaction in the UK, and even with postage (registered to delivered by EMS here), they were still cheaper than what I pay for Conti GPS II's here.   Tubeless allows lower pressure with no loss of speed (in fact these are faster than the Conti's, and I always seem to be in a higher gear than is usual), and the small amount of sealant inside takes care of any punctures.   It would have to be something catastrophic to a tyre to halt a ride, which of course would be the case with clinchers also.

[CNXBKKMAN]

4 hours ago, pagallim said:

Agree with Nowisee re tubeless.   I have Schwalbe Pro One tubeless on both of my road bikes now and they are excellent.   Got them on special offer from Chain Reaction in the UK, and even with postage (registered to delivered by EMS here), they were still cheaper than what I pay for Conti GPS II's here.   Tubeless allows lower pressure with no loss of speed (in fact these are faster than the Conti's, and I always seem to be in a higher gear than is usual), and the small amount of sealant inside takes care of any punctures.   It would have to be something catastrophic to a tyre to halt a ride, which of course would be the case with clinchers also.

How much did customs tab onto the delivery. Did they sail through with no tax added? 

[richard_smith237]

I'm 95kgs on 30mm tires I run 80-85psi... for regular use. This offers a slight softer ride around the parks etc (Lumpini, Benjakitti or over on Bang Krachao). 

 

When on the skyline I would increase this to 100psi on a much smoother surface. 

 

That said. I haven't actually checked my tyre pressures in over a month !... I'm too lazy to inflate then deflate my tires after every ride. 

 

 

[pagallim]

3 hours ago, CNXBKKMAN said:

How much did customs tab onto the delivery. Did they sail through with no tax added? 

OK, Chain Reaction have the option of regular (Registered Mail/EMS) or Express (DHL/Fedex etc).   No duty was charged on regular mail (both occasions I've used them).  Couriers such as DHL etc, are obliged to collect import duty on behalf of Thai Customs, which they calculate on the accompanying invoice/receipt.

[oldwelshman]

80 to 100 is fine, higher pressure bumpier ride on uneven surfaces, also increase risk of pinch punctures. No real benefit in high pressure.

[StreetCowboy]

21 hours ago, oldwelshman said:

80 to 100 is fine, higher pressure bumpier ride on uneven surfaces, also increase risk of pinch punctures. No real benefit in high pressure.

I don't agree with the "higher risk of pinch punctures".  I believe that these are caused by having your tyres too soft.  I don't know what pressure is too soft on 25 mm road tyres, but I wouldn't recommend running any less than 80 psi on them.  Not unless you're a dainty fairy like Tinkerbell.

 

I used to get loads of punctures on my road bike, until I got a floor pump and started pumping them up to the top end of the marked range - about 75 - 80 psi.  I don't know what they were at before, but probably about half that.

 

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[oldwelshman]

4 hours ago, StreetCowboy said:

I don't agree with the "higher risk of pinch punctures".  I believe that these are caused by having your tyres too soft.  I don't know what pressure is too soft on 25 mm road tyres, but I wouldn't recommend running any less than 80 psi on them.  Not unless you're a dainty fairy like Tinkerbell.

 

I used to get loads of punctures on my road bike, until I got a floor pump and started pumping them up to the top end of the marked range - about 75 - 80 psi.  I don't know what they were at before, but probably about half that.

 

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Wider tyres need less pressure. In Parie Roubaix they use wider tyres with not much pressure, less than 80psi. On a track I use 140psi but on road 100 in rear 90 front and check and re inflate after couple of weeks, been as low as 45 lol

[el jefe]

 

On 8/3/2017 at 10:32 AM, StreetCowboy said:

I don't agree with the "higher risk of pinch punctures".  I believe that these are caused by having your tyres too soft.  I don't know what pressure is too soft on 25 mm road tyres, but I wouldn't recommend running any less than 80 psi on them.  Not unless you're a dainty fairy like Tinkerbell.

 

I used to get loads of punctures on my road bike, until I got a floor pump and started pumping them up to the top end of the marked range - about 75 - 80 psi.  I don't know what they were at before, but probably about half that.

 

SC

 

oldwelshman said

Wider tyres need less pressure. In Parie Roubaix they use wider tyres with not much pressure, less than 80psi. On a track I use 140psi but on road 100 in rear 90 front and check and re inflate after couple of weeks, been as low as 45 lol

@oldwelshman:

yes, wider tires allow you to run lower pressure, but higher pressure does not lead to "higher risk of pinch punctures". Pinch punctures happen when an under-inflated tire hits an obstacle and pinches the tube between the rim and the road. Switching to wider tires can help. But if you're using 700 x 23 tires, reducing the pressure will only increase the risk.

[junglechef]

On 2/24/2017 at 10:27 AM, StreetCowboy said:

 

[junglechef]

On 5/19/2017 at 3:57 PM, pagallim said:

OK, Chain Reaction have the option of regular (Registered Mail/EMS) or Express (DHL/Fedex etc).   No duty was charged on regular mail (both occasions I've used them).  Couriers such as DHL etc, are obliged to collect import duty on behalf of Thai Customs, which they calculate on the accompanying invoice/receipt.

How long did the mailing take?

[pagallim]

2 hours ago, junglechef said:

How long did the mailing take?

From recollection, less than 2 weeks by regular (Registered) mail.