# Correlation between Tire Pressure and Acceleration of a Motorbike

• bagasme
In summary, there is a discussion on Stack Exchange about the correlation between tire pressure, loadout (such as riders), and acceleration of a motorbike. The conversation mentions that tire pressure can affect load sensitivity and that total rider mass is important for power-limited acceleration. The addition of a passenger can potentially increase rear wheel loading and improve traction on certain surfaces. However, for most motorcycles, acceleration is not grip limited and is instead limited by other factors such as rear swingarm geometry and center of gravity.

#### bagasme

I have asked this question on Stack Exchange: SE question.

I often encountered this sticker on most motorbikes (especially matic ones) [credit: cintamobil.com]:

There, when the tire pressure was measured from cold condition, the tire pressure are same regardless of loadout (29 psi and 33 psi for front and rear tire respectively).

According to SE:
The acceleration of the bike is given by the torque of the engine and the mass of the bike plus passengers - so when you have a passenger, there is greater inertia to overcome and your acceleration will be less
The force of friction is typically (naively) modeled by Ff∝μN
, whether static or kinetic (while both of these forces are vectors, the normal force acts perpendicular to the surface while friction acts in some direction parallel to the surface). If engine/gearbox can put enough torque on the axle to spin the wheels out, then the acceleration is capped not by the drive-train, but by the friction between the drive wheel(s) and the road.

Most tire manufacturers recommend a tire pressure which balances the durability of the tire's sidewall and the increased gas mileage of an over-inflated tire with the added comfort, acceleration and braking of a slightly less inflated tire (see rolling resistance). Obviously, tires either too flat or too full are a safety hazard.
If the engine/gearbox are powerful enough, the center mass hasn't moved too high and the connection between the road and the wheels exceptionally tight, one could see greater acceleration with a passenger.

Is it true that tire pressure and loadout (e.g. riders) correlate with acceleration of motorbike? Are there any papers that explain about it?

Regards, Bagas

bagasme said:
Is it true that tire pressure and loadout (e.g. riders) correlate with acceleration of motorbike? Are there any papers that explain about it?
Tire pressure will figure into load sensitivity.

As indicated above, for power-limited acceleration, total rider mass is crucially important.

The passenger will be toward the rear of the bike. Adding the passenger could thereby increase rear wheel loading proportionally more than front wheel loading, gaining more through traction than is lost due to the extra mass. On some surfaces, (snow, slush, water sufficient to hydroplane), the weight of the passenger could help the wheels "cut through" and get some purchase on the road beneath.

For most motorcycles, acceleration isn't grip limited anyways, so all of those factors are irrelevant. Acceleration is limited by rear swingarm geometry, suspension, and CG location, since the limiting factor is the acceleration at which the bike will wheelie and flip over backwards.

jbriggs444

## 1. What is the correlation between tire pressure and acceleration of a motorbike?

The correlation between tire pressure and acceleration of a motorbike is a positive one, meaning that as tire pressure increases, acceleration also increases. This is because higher tire pressure results in a larger contact patch between the tire and the road, providing better grip and allowing for quicker acceleration.

## 2. How does tire pressure affect the handling and stability of a motorbike?

Tire pressure plays a crucial role in the handling and stability of a motorbike. If the tire pressure is too low, the tire will be more susceptible to deformation and may not maintain its shape during cornering, leading to a loss of stability. On the other hand, if the tire pressure is too high, the tire may not be able to absorb bumps and imperfections on the road, leading to a rough and unstable ride.

## 3. Is it necessary to adjust tire pressure for different riding conditions?

Yes, it is essential to adjust tire pressure for different riding conditions. For example, if you are riding on rough terrain, lower tire pressure will provide better traction and stability. In contrast, if you are riding on smooth roads, higher tire pressure will result in better fuel efficiency and handling.

## 4. Can tire pressure affect the lifespan of a motorbike's tires?

Yes, tire pressure can significantly impact the lifespan of a motorbike's tires. If the tire pressure is too low, the tire will wear out more quickly due to increased friction and heat. If the tire pressure is too high, the center of the tire will wear out faster, resulting in decreased traction and handling.

## 5. How can I measure and maintain the correct tire pressure for my motorbike?

To measure and maintain the correct tire pressure for your motorbike, you will need a tire pressure gauge. You can find the recommended tire pressure for your motorbike in the owner's manual or on a sticker located on the bike. It is essential to check and adjust tire pressure regularly, especially before long rides, to ensure optimal performance and safety.