We know that the air pressure in tires have nothing (at least not directly) to do with the designations in meteorology of high pressure and low pressure.
The tire pressure, on the other hand, is responsible for driving safety. What happens if the tires of our scooter do not have the correct air pressure?
Too little air in the tire could:
- adversely affect driving stability (increase pitching moment during braking and steering force when leaning)
- increase the braking distance
- increase the risk of skidding
- promote dangerous tire damage/blowouts
Besides the safety implications, low tire pressure can also increase fuel consumption.
Too much air pressure could:
- increase the risk of a tire blowout
- accelerate the wear of the tire
- increase the braking distance (smaller contact area of the tire)
- promote crashes (aquaplaning)
We note: too much or too little air, it affects in any case the driving behavior of our scooter and affects the safety.
What is the correct tire pressure?
The correct air pressure in tires depends on some circumstances:
- weight load of the scooter
- riding solo or with pillion
- Load due to luggage
- driving behavior of the rider
- condition of the road (tar, concrete, cobblestones/gravel etc.)
What we all do wrong again and again or omit out of convenience: We check the air pressures far too seldom. But it would be so simple: use gas stations not only to top up with fuel, but also to check tire pressure.
Do not forget to check the air pressure:
Air heats up and expands!
For this reason, if possible, measure the tires in a cold state and pump up. This is also what tire manufacturers do, which is why their recommended values are based on cold measurements.
Recommendation for the correct tire pressure
Air pressure at the front approx. 2.0 bar, at the rear 2.5 bar, in each case recommended for solo driving. Depending on the tire manufacturer, the maximum pressure is stamped on the tire.
The specified standard air pressure does not necessarily correspond to the air pressure that leads to optimal function of the tires. Not so long ago, manuals for two-wheelers often gave 2 different specifications for air pressure:
Values for solo rides on the one hand and rides with pillion and/or luggage on the other. This has obviously been too much effort, which is why in more recent times mainly the high air pressure are presented.
What does the optimum air pressure depend on?
This question is relatively easy to answer: from the tire construction and the respective purpose.
Bar or psi, what does it mean?
Sometimes the air pressures are given in bar or in psi (depending on the manufacturer), how can I convert that?
Good question, here is the solution:
1 bar ≈ 14,504 psi
1 psi ≈ 0,069 bar
Simple conversion formulas
For a quick conversion, it pays to have this kure formula in a note:
Conversion bar to psi: bar value x 14.504
Conversion psi to bar: psi value x 0.069
Why do we need different units of measurement?
We don’t really need them, they each have different origins. The abbreviation for psi is English: pound-force per square inch. It is enough to know that this measure of tire pressure is of Anglo-American origin.
The term ‘bar’ can be found on pressure washers, compressors and, as here, on tires. It comes from the Greek báros and means weight, pressure.
Ultimately, we should remember the Vespa philosophy:
Comfortable riding in beautiful surroundings, as befits a well-behaved scooter.
After all, that’s what the scooter was designed and built for. Whether the bike now goes 3, 4, or 5 km/h faster (when fully pumped up) or not, who cares. The ‘normal’ Vespisti in any case hardly. What we do care about is driving safety, which is always our top priority. We stick to the air pressure values recommended by the tire manufacturer and our manual, then we don’t do anything wrong.
We also take it upon ourselves to check the air pressure more often. That much time has to be!