MAK

I realize that this is either an excellent question or a really dumb one. Never-the-less...

It occurs to me that tires will be most supple when warm and stiffer when cold. I usually run my 23c Conti 4000s at 115-120 psi in the summer. When the temperature goes into the 30s and below, do any of you adjust tire pressure due to the ambient temperature? If you do make an adjustment, how large an adjustment and at what temperature do you adjust?

bikerjp

I don't adjust them at all. However, you may be running too high a pressure to start with. I'm 200lbs and run 90-100psi summer and winter.

escarpment

I notice that tires become a bit softer in the cold, I dont compensate though.

Trsnrtr

Why would you alter it in the Winter? PSI is PSI, regardless of the season. Ambient temperature makes no difference in this case unless you're pumping your tires at 0F in the morning and then finishing the ride in the evening at 100F.

Even then, pressure would only rise 10#.

merlinextraligh

How would a tire with the same pressure become softer when it was colder.

All else equal colder tires are harder and have less grip. Whether the effect is significant enough on a bicycle to worry about is debateable.

Perhaps the actual pressure you're running in the tires is lower because of the lower temperature, which in effect means you are compensating thanks to Charles' law.

lsberrios1 

I run 120PSI on my 700x25...

gerundium

i run lower pressure in winter due to leaves and mud being abundant on the road. whatever effect colder temps have on your tires seems insignificant compared to the leaves and mud.

Rootman

The tire compound should be stiffer but the cold air is denser and occupies less space in the tire, if it actually reduces enough to be noticeably is another point of debate.

carpediemracing 

I like the way you worded the question.

In cold temps I'm not sophisticated enough to tell if the rubber is losing traction. I have summer tires for my car so I totally understand where you're coming from. For those that have had only all-season tires summer tires turn into wood at about 30-35 degrees, losing virtually all their traction at that point. It's like driving on oiled up roads, significantly worse than driving on wet roads - I could break my tires loose in second gear from a stop in a car that would lug in dry weather if I did that. All seasons retain traction even when it's cold.

If you're running normal rims (20mm wide at braking surface) then your pressures are probably fine. If you have some wide rims then you could probably go lower, pending your weight. I ran, at 150-215 lbs, about 120 psi in my 23c clinchers on regular 20mm rims. I run now, at 160-180 lbs, 95-105 in my 23c clinchers on 23mm rims. I'm experimenting with lower pressures and have run as low as 60-70 psi (175 lbs) but I don't feel comfortable recommending that to others.

I think that bike tires are "all season" generally speaking. I've never had a tire wash out from under me in the cold when I expect it to hold.

I tend to err on the high side for pressure when riding in winter simply because I don't want to flat. If I'm cold in the parking lot then it's winter to me, so that's in the high 30s or low 40s. If my chin will go numb on the ride then it's definitely winter.

Looigi

A 30 F decrease in temp, saying airing up inside at 70F and going out to ride in 40F, will decrease tire pressure by 30/562 (Rankine) = ~5%. So 100 becomes 95psi.

Sixty Fiver

The tyre compound plays a very important role in how well any given tyre works in cold temperatures.. some remain supple at lower temps and this aids traction and improves the ride quality.

Proper inflation is a function of rider weight and load and the road conditions... reducing tyre pressure can aid traction and improve the ride and road handling properties of the bicycle.

Temperature changes do not affect tyres to any significant degree as they have such a low air volume.

Drumnagorrach

Lowering tyre pressures increase your chance of a tube nip. I have tried reducing pressures a tad to relieve the vibration from bad surfaces,but now my riding is almost entirely in the dark,I have clipped large chunks of gravel in the road( just couldn't see them in time)and suffered a rear tube nip.

Sixty Fiver

Lowering tyre pressure below what the tyre can support will cause pinch flats... sometimes small changes in psi yield some impressive improvements and would not suggest you ride your road bike with 30psi.

I find that most people ride with too high a pressure in their tyres, not understanding the principle of deflection and just going with the idea that higher pressure equals going faster.

MAK

This (and some of the others) is the kind of answer I was looking for. Bottom line is that it appears that I should put 5 or so more psi in when riding in the cold because I do pump indoors before venturing out.

Thank you and the others that replied.