A tire is a pneumatic system, which supports a vehicle's load. It does
this by using a compressed gas (usually air) inside to create tension in
the carcass. It is important to realize that a tire carcass has a
high-tension strength, but has little or no compression strength. It is
the air pressure that creates tension in the carcass and allows the tire
to function as a load-carrying device. That's why inflation is so
The tire does not support the load-the air pressure does. The
manufacturer's ratings for the maximum load and inflation pressure are
critical tire design elements. If not observed, the handling and
performance of your motorcycle will be greatly affected.
Two points to remember:
A tire must transmit handling (acceleration, braking, cornering) to
A tire also acts as a spring between the rim and the road. This spring
characteristic is very important to the vehicle's ride.
Under inflated tires can result in imprecise cornering, reduce ability
to support the load (traction), higher running temperatures, irregular
tread wear at the edge of the contact patch, fatigue cracking,
overstressing and splitting in the sidewall.
Special Note: If splitting happens on the inside of the tire and is
hidden from your sight, then it can spread and eventually result in a
blister and blow out of the sidewall. This sudden deflation may cause
loss of control with serious consequences.
Over inflating tires does not increase load carrying capacity, but will
result in a hard ride through the transmitting of shock loads to the
suspension, reduces the a tire’s ability to withstand road impacts, and
cause accelerated tire wear in the center of the contact patch.
Air pressure is affected by temperature. The air under pressure in a
tire is no exception. Typically, an inflation pressure can change by 1
psi for every 10 degrees Fahrenheit of temperature change. Higher
temperature means increased pressure.
For example, if a tire is inflated to 35 psi on an 80-degree day in
July, it could have an inflation pressure of 23 psi on a 20-degree day 6
months later in January. This represents a normal loss of 6 psi over the
six months and an additional loss of 6 psi due to the 60-degree
temperature change. At 23 psi, this tire is severely under-inflated.
If the rear tire is inflated to 40 psi on a summer morning with a temp
of 60 and a high of 90-degrees--tire pressures can reach around 44 psi
possibly exceeding the tire’s maximum rating.
Checking Tire Pressure
How does one go about checking tire Pressure? Several factors determine
recommended tire pressure: Weight, ambient temperature, road conditions,
and comfort (handling) Each factor must be considered when adjusting
Check cold tire pressure frequently with a good quality gauge that holds
a reading, and always before extended trips.
Check your pressures daily when you are on a trip and remember that
every 1 psi of air lost is approximately equivalent to losing 60 or 70
pounds of load carrying capacity.
Heavier loads-dual riding and/or luggage
For high-speed, fully loaded or dual-riding touring motorcycle
applications, inflate front tires to maximum recommended by vehicle
manufacturer for OEM fitment and rear tires to maximum load inflation
pressure on sidewall. Notice that that front tire is inflated to the
motorcycle manufacturer recommendation, not the sidewall. This is the
optimal pressure for best braking performance under the load conditions
tested by the manufacturer.
Another rule-of-thumb is to increase both front and rear tire pressure
by 2 psi for every 100 lb. (up to maximum motorcycle load capacity
stated in the owner’s manual.) All increases to tire pressures are
usually within 4 psi of motorcycle manufacturer recommendation for an
unladen motorcycle but never exceed maximum pressure stated on tire.
Making life simple
Check the tire pressure in the morning before a ride. If the ambient
temperature is between 50 to 60 degrees; set the psi to motorcycle
manufacturers specs for OEM tires. Any variance in conditions usually
takes care of its self after that with the exception of extreme load
changes and adjustments for rain, snow, dirt, or grass.
What if my tires are not OEM?
Call the Tire manufacturer and say the following:
Hi my name is [that would be you]. I recently bought your [Model] tires
for my [make, model, year] and was wondering what the recommended
inflation is with an ambient temperature of 50-degrees Fahrenheit and [
x pounds—that’s your weight] of load.
After he/she recovers from the shock of your remarkable intelligence,
you will have your baseline for making adjustments to tire pressure.
Thanks to Dunlap and Metzeler for providing technical data.
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