Flats – At lower pressures the tire has less umph keeping the rim off of the ground. Thus you are more likely to hit something that pinches the tire between the rim and the offending object creating a hole (or a snake bite, two holes). At higher pressures, there is less give in the tire and sharp things on the road now punches through and punctures the super hard tire (versus less pressure allowing the tire to deform around said pokey object).

– At lower pressures the tire has less umph keeping the rim off of the ground. Thus you are more likely to hit something that pinches the tire between the rim and the offending object creating a hole (or a snake bite, two holes). At higher pressures, there is less give in the tire and sharp things on the road now punches through and punctures the super hard tire (versus less pressure allowing the tire to deform around said pokey object). Ride – Similar to the flats logic, less air pressures allows for more deformation in the tire when it encounters less than perfect road conditions. The squishy tire leads to a more comfortable ride by “absorbing” the road inconsistencies and sending less vibrations to you. More pressure is the opposite and supposedly will rattle your teeth out of your face.

– Similar to the flats logic, less air pressures allows for more deformation in the tire when it encounters less than perfect road conditions. The squishy tire leads to a more comfortable ride by “absorbing” the road inconsistencies and sending less vibrations to you. More pressure is the opposite and supposedly will rattle your teeth out of your face. Resistance – As you increase the tire pressure, it deforms less and rolls easier (this notice the pressure related theme?). With less deformation, there is less rolling resistance and you go faster given the same effort. It is often stated that there is an upper limit to reducing rolling resistance by increasing tire pressure.

Table that Summarizes the Pressure Trade-offs Trade-off Low Pressure High Pressure Flats Pinch Puncture Ride Smoother Rougher Resistance Higher Lower

There are people out there that can test and find the upper pressure limits and find the pressure that give the trade-offs just mentioned (e.g. the skinny guy). They say that to truly find the negative side of high pressure you will need somewhere around 20% more pressure that predicted by this calculator. For me, the upper pressure limit is not achievable due to the certain explosion; due to the 185+ psi needed for me to hit 20% more than the recommended limit (for a 23 mm tire).



Tire Pressure Misinformation (at least for us Clydesdale’s)

If one should Google road bike tire pressure, one gets information that ranged from less than applicable to outright wrong, for the big guy. For instance consider the following non-sense ( my Clydesdale opinion is in blue):

I have ridden for 40 years and never have gotten a pinch flat @ 95 psi… Well for my 250 lb body, I don’t get pinch flats with a rear tire more than 135 psi.

You lose traction at anything over 120 psi… Well tubby here has ridden my road bike in all conditions (except ice, really ’cause why) at 135-145 psi and never lost traction. Maybe that once on gravel.

You get more puncture flats at higher pressures… I switched to gator skins and did not get a flat in 2 years putting 100 miles a week in the summer (50 in the winter) riding well above the max listed 120 psi.

They put the recommended tire pressure for you to ride with on the side of the tire… Well? Huh? Anyway, I routinely exceed the listed maximum pressure and have not had any serious blowouts in the past, but to each his/her own.

Where did this calculator come from, Are you an Idiot?

I came across a lot of references and ended up plotting about five of them in excel and averaging the results. This resulted in a mess, so I performed linear regression on a Bicycle Quarterly article Optimizing Your Tire Pressure for Your Weight. This resulted in a calculator that seems to represents my experience.





Weight on rear tire?

I did not like their weight distribution chart, as it seemed random. So I figured out a way to check at home with no extra stuff. For me loaded, I have 55% of my weight on my back wheel. I checked this by putting a bathroom scale under each tire then getting on my bike and balancing in a hallway (with as little help from the wall for balance as possible). My wife then read me the weight from each scale and I did the simple math.





Did You Gain Any Extra Insight from Making This Post?

Go Bigger – I finally got a pair of 25 mm tires for the first time, we will see how that goes. Some others (continental tires) claim that the 25mm tire has less resistance than the 23mm (for the same operating pressure).

The Alter of Rolling Resistance – It seems that many people are into buying the tire with the lowest rolling resistance. I favor tires that are bullet proof. As indicated above it seems that higher pressures = more puncture flats. I switched to GatorSkins and found that I enjoy the lack of flats more than the perceptible increase in rolling resistance? I used a couple of online cycling calculators and found that the Gatorskins cost me ~0.4 mph in a perfect world (20/19.6 mph). Throw in some hills and wind and the difference becomes less noticeable.

On a 70.3 course the time difference is ~3 minutes, one flat costs more than that and is more super annoying.

Personal Preference – You need a place to start, but it seems that the best tire pressure is a personal thing… so use this Calculator to get a good starting point and then go with more pressure or less pressure till everything is perfect. Also note that you may want to run 20% more pressure on a new smooth concrete road than an old chipcrete one.