In general, the inflation pressure required at a given temperature is dependent upon travel speed and vertical load on the tire. The standard tire used on the Ventrac 4500 is an ATV tire and is rated for speeds far in excess of the 10 mph top speed of the tractor. So it boils down to load. For most operations of a 4500 with single tires, 8 psi is both adequate and desirable. The lower the inflation pressure the greater the footprint area which translates to greater traction and greater braking capability. For operation on turf, the lower the inflation pressure, the smaller the amount of soil compaction produced, so it is really important to use the correct low pressures when mowing. Ventrac Operators Manuals formerly specified 8 psi for most single tire operations. The big exception is when a Versa-Loader is mounted. Then the Loader Operators Manual calls for inflation pressures of 15 psi. So for using a broom or snowblower 16 psi is way too much. The front tires only support the maximum load in transport, and the amount of time spent in transport on a driveway and into the garage is very small, so seeing a bulge in the front tires when the broom or blower is raised like shown in JJVs photo is not a call for alarm.
Inflation pressure is influenced by ambient temperature with the general rule of thumb being that the pressure will change by 1 psi for every 10 degree F increase or decrease. Tire Tech Information - Air Pressure, Temperature Fluctuations
So if you set the inflation pressure to 8 psi when the temperature is 50 degrees, when the temperature drops to 20 degrees, the pressure will drop to about 5 psi. This is why it is imperative that inflation pressure be checked and reset as ambient temperatures change seasonally. All pressures published in the tables issued by the Tire and Rim Association are "cold" pressures--the inflation pressures required for a given load and speed when the tire is cold. As the tire is worked in the summer it heats up and the pressures rise, so if you set the pressure at the hottest time of day, you use a little more than called for. Then as the temperature drops it arrives at the specified "cold" pressure.
It is also important to use an inflation pressure gauge that is accurate in the range where you are setting pressures. The typical gauges used for car and truck tires are not usually accurate for the low pressures required on turf equipment. A simple stick gauge for the range 0-20 psi is a good inexpensive solution. Some digital gauges also are accurate in this low range. You just have to be careful in selecting a gauge that is appropriate for the pressure range of interest.
In early December when I prepare my 4500 for winter operations with the V Blade and Snowblower, I set the inflation pressures to 10 psi and monitor the tires in extremely cold weather to assure the pressures stay at 8 psi or above. This works well, but requires vigilance in looking at the tires each time before starting out to begin work after a snow storm. I am quite willing to do this. Some others may not be.
JackIL
Inflation pressure is influenced by ambient temperature with the general rule of thumb being that the pressure will change by 1 psi for every 10 degree F increase or decrease. Tire Tech Information - Air Pressure, Temperature Fluctuations
So if you set the inflation pressure to 8 psi when the temperature is 50 degrees, when the temperature drops to 20 degrees, the pressure will drop to about 5 psi. This is why it is imperative that inflation pressure be checked and reset as ambient temperatures change seasonally. All pressures published in the tables issued by the Tire and Rim Association are "cold" pressures--the inflation pressures required for a given load and speed when the tire is cold. As the tire is worked in the summer it heats up and the pressures rise, so if you set the pressure at the hottest time of day, you use a little more than called for. Then as the temperature drops it arrives at the specified "cold" pressure.
It is also important to use an inflation pressure gauge that is accurate in the range where you are setting pressures. The typical gauges used for car and truck tires are not usually accurate for the low pressures required on turf equipment. A simple stick gauge for the range 0-20 psi is a good inexpensive solution. Some digital gauges also are accurate in this low range. You just have to be careful in selecting a gauge that is appropriate for the pressure range of interest.
In early December when I prepare my 4500 for winter operations with the V Blade and Snowblower, I set the inflation pressures to 10 psi and monitor the tires in extremely cold weather to assure the pressures stay at 8 psi or above. This works well, but requires vigilance in looking at the tires each time before starting out to begin work after a snow storm. I am quite willing to do this. Some others may not be.
JackIL
