Weather conditions do play a big part in tyre pressures. If it’s a lovely sunny day and there is no debris or water on the road, pressures can be at their optimal pressures (this will vary for each rider and tyre choice so check the manufactures claims) if the conditions are somewhat variable on a winter’s day for example. Running slightly lower pressures than the standard estimations in this case will help keep grip where the terrain is affected by things like leaves, mud, gravel and water.
If you are really fanatical about tyre pressures vs air temperature like the F1 teams may be so particular about, then when you pump up your tyres in the garage the air will be warm when entering the tyre, once you take your bike out into sub zero temperatures you will lose some of that air. So just take this into consideration if the temps are very low so you don’t run the risk of pinch flats.
Hill gradient is an element which can determine which tyre pressures to run with. Steep ascents require a little extra grip due to your weight transferring over the front of the bike when climbing and so your rear wheel becomes lighter and loses grip, In this instance run the pressure ever so slightly lower to increase the amount of grip you have. (see graph for figures) The same extent of grip is needed when descending too because of weight transfers, most notably on sharp, steep bends where you’ll need to grip on the corners.
With tyres and rims now getting wider and wider nowadays you should be running lower pressures. research has shown that wider rim and tyre are now more aerodynamic than a narrower tyre and have more benefits such as more grip. So, think of it like your car tyre or a mtb tyre. Because there is a lager surface area you don’t need as much pressure to get the same effect. When running a wider tyre there is more contact points on the surface of the road, so in this instance you would also naturally have more grip too. This would particularly be beneficial on cobbled roads or an uneven terrain.
We don’t need to be shy or polite, some riders are naturally lighter or heavier than one or another. That’s just nature and how we differ from one another. Maybe you carry luggage or have a nice steel bike that weighs a little more than a super light carbon bike. Either way this does contribute to road bike tyre pressures too.
If you are super light then you may not need as much pressure in your tyres as a heavier rider would. It may be quite a harsh ride for a lighter rider if you are at over 110 PSI.
On the flip side of that a heavier rider may hit pot holes, bumps, and so on, with much more force which means that they’d be prone to more punctures or blow outs if the pressure is too low.
There are various different types of set ups which will change the air pressure in which you decide to run with. Different tyres require different pressures:
Tubular bicycle tyres are completely sealed all the way around and are glued onto a tubular compatible rim. This type of tyre generally runs at higher pressures than any other tyre, simply because of the nature of the profile which can accommodate a higher pressure. This however does work the opposite way – in cyclo-cross, riders choose to use tubs as pressure can be run very low to aid in grip. This is mainly down to the fact that they cannot pop off the rim or suffer pinch flats like a clincher tyre can.
Clinchers with tubes fitted are the most common tyre set up amongst the everyday rider and are normally run around 90-120 PSI depending on varying factors.
This is a tyre that is fitted to a tubeless compatible rim and is run with sealant inside the tyre to help seal punctures whilst on the go. Pressures can be run very similar to normal clincher tyres but are less likely to suffer pinch flats and are the most reliable when out on the road as they can be easily fixed. Pressures on tubeless tyres are generally run very similar to tubed clinchers but can be run lower if required as there is lower risk of pinch flats.
One final thing to consider
One of the biggest misconceptions on tyre pressure is that the higher the pressure the faster you will go. This is not the case.
There have been many studies to prove that in finding the optimum pressure for your combined bike and weight is vital in getting the lowest rolling resistance out of your bike. There does become a point in which too much pressure can have the opposite effect.
If you are looking for the most accurate tyre pressures for the day then Vittoria have a fantastic app to tell you exactly what you should be running.