The summer months of July and August can take a serious toll on your tires. Treadwear is more rapid because of the combination of higher ambient and higher road surface temperatures, and heat has always been a tire’s worst enemy. Maintaining proper tire pressures is always important to maximize treadwear, fuel economy, and retreadability. In the summer time, it is even more critical. Keeping the tire running “cool” is the key to success.
Rubber on the road, more commonly called “road alligators,” increase dramatically on the nation’s highways during the summer driving season. The majority of the motoring public clearly believes that these road alligators are caused by bad retreads; this is just not accurate. The alligators on the road could be new tires or, maybe, retreads. If either a new tire or retread is running underinflated based on the vehicle load and speed for an extended period of time, that tire can fail with the result a road alligator.
Air is what carries the load in a tire. The tire manufacturers all publish a load-inflation table that lists the maximum load/tire for a given pressure. A tire with little or no air is eventually going to fail. Those inside dual trailer tires (new tires or retreads), which are the least maintained tire on the vehicle when it comes to maintaining proper tire pressure, are often the biggest culprit based on historical industry studies of rubber on the road analysis. These same industry studies have clearly shown that 90% of the rubber on the road is and continues to be tires run underinflated. There are really only three reasons why a tire loses air:
- Tread area punctures;
- and Valve stem and valve core leaks.
Just like a balloon, a tire will lose air by osmosis through its casing. Depending on the tire make/model, commercial tires will lose 1–2 PSI per in July; doesn’t sound like very much. Over a year, that will add up to be as high as 24 PSI. Running a commercial truck tire with a target pressure of 100 PSI 24% underinflated on a fully loaded vehicle at 65 MPH or faster in the middle of Texas in August is not a good combination.
Industry tire pressure surveys suggest the poorest air pressure maintenance practices occur on trailer tires as the poorest. Inside dual trailer tires usually have the lowest measured tire pressures. Inside dual trailer tires at 70 PSI and outside duals at 100 PSI is not uncommon. This leads to significant amount of irregular wear and early tire removals because of the difference in tire revolution per mile of the two tires running at the different operating pressures.
Depending on the specific tread area puncture, in addition to losing 1-2 PSI in July due to osmosis, a slow leaking puncture, which penetrated the groove of a tire, may lose 3-4 PSI or more per day. Within a week, you can have a big issue. Punctures in the tread area are the number one reason why tires lose air. The old number 20 penny nail is the main culprit when it comes to punctures.
Valve cores have been known to stick, which can cause loss of air. Over tightening valve cores is also a known problem. Torquing a valve core more than the recommended 4 in.-lbs. can also result in loss of tire air pressure.
Fleets need to develop a serious tire pressure maintenance program as part of their overall tire program. Inspecting and checking pressures on a regular basis is very important. Drivers are the early warning system when it comes to monitoring tire pressure. During the driver vehicle walk-around, tires need to be visually inspected and checked with a calibrated air pressure gauge. Using a “club” is not sufficient to identify an underinflated tire. Tire pressure monitoring systems and automatic tire Inflation systems continue to increase in popularity.
Emergency tire roadside service calls drop dramatically when tires are properly inflated, so it is always a good idea to work with your tire professional to develop a solid tire and tire pressure program for your fleet.